TWI651583B - Photomask substrate, method for manufacturing photomask substrate, phase shift mask, method for manufacturing phase shift mask, and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention provides a photomask substrate for a phase-shifting photomask, which is provided with an etching stop film that satisfies the following characteristics: the resistance to dry etching using a fluorine-based gas used in forming a phase-shifting pattern is higher than that of a light-transmitting substrate It also has higher resistance to chemical liquid cleaning and higher light transmittance to exposed light.

The photomask base of the present invention is characterized in that it is provided with a light-shielding film on a main surface of a light-transmitting substrate, and has a structure in which an etching stop film, a phase shift film, and a light-shielding film are sequentially laminated on the light-transmitting substrate The phase shift film contains a material containing silicon and oxygen, and the etch stop film contains a material containing silicon, aluminum and oxygen.

Description

Photomask substrate, method of manufacturing photomask substrate, phase shift mask, method of manufacturing phase shift mask, and method of manufacturing semiconductor device

The invention relates to a photomask substrate, a phase shift photomask manufactured using the photomask substrate, and a method for manufacturing the same. The present invention also relates to a method for manufacturing a semiconductor device using the phase shift mask.

Generally, in a manufacturing step of a semiconductor device, a fine pattern is formed using a photolithography method. A number of transfer masks are usually used in the formation of this pattern. Especially in the case of forming a fine pattern, a phase shift mask is used which improves the transfer performance represented by resolution by utilizing a phase difference. In addition, when miniaturizing the pattern of a semiconductor device, in addition to the improvement and improvement of a transfer mask typified by a phase shift mask, it is also necessary to shorten the wavelength of the exposure light source used in photolithography. . Therefore, in recent years, the exposure light source used in the manufacture of semiconductor devices has been shortened from KrF excimer laser (wavelength 248 nm) to ArF excimer laser (wavelength 193 nm).

An etching Levenson type phase shift mask as one aspect of a phase shift mask includes a light transmitting portion including an etched portion and a non-etched portion formed on a light-transmitting substrate, and a line and a gap are formed. The shading of the pattern. Specifically, a light-shielding portion is formed in a region where a light-shielding film is present on the light-transmitting substrate, and a light-transmitting portion is formed in a region where the light-transmitting substrate without a light-shielding film is exposed. The etching depth of the etched portion becomes a depth capable of imparting a specific phase difference that can obtain a phase shift effect between light exposed through the etched portion and light exposed through the non-etched portion. Previously, as disclosed in, for example, Patent Document 1, the phase shift mask of the etched Levinson type was made by Manufactured on a transparent substrate with a mask base provided with a light-shielding film containing a chromium-based material.

On the other hand, Patent Document 2 discloses a method for manufacturing a Levinson-type phase shift mask using a laminated film. In this method, a transparent conductive film including alumina (Al ₂ O ₃ ), a transparent phase shift film including SiO ₂ , and a light-shielding film containing Cr as a main component are sequentially formed on a transparent substrate including quartz on a transparent substrate including quartz. Film, forming a pattern of the main light transmitting portion and an auxiliary light transmitting portion on the light shielding film, and then forming a pattern of the auxiliary light transmitting portion on the phase shift film.

Defects in a transfer mask, such as a phase shift mask, are directly related to defects or reduction in yield of a semiconductor device manufactured using the transfer mask. Therefore, when a defect is found in the transfer mask, the mask defect is corrected. As this mask defect correction technology, Patent Document 3 discloses that a black defect portion is made by supplying xenon difluoride (XeF ₂ ) gas to a black defect portion facing a light-shielding film and irradiating an electron beam to the portion. Defect correction technology for etching and removal (hereinafter, such defect correction by irradiating charged particles such as an electron beam is referred to as "EB defect correction"). The EB defect correction was originally used to correct black defects in the absorber film of reflective masks used in EUV lithography (Extreme Ultraviolet Lithography), but in recent years it has also been used to correct defects in phase shift masks.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 9-160218

[Patent Document 2] Japanese Patent Laid-Open No. 2006-084507

[Patent Document 3] Japanese Patent Publication No. 2004-537758

The previous etched Levinson-type phase-shifting mask is configured to form an etched portion and a non-etched portion on the substrate, and generate a phase between the light exposed through the etched portion and the light transmitted through the non-etched portion Shift effect. Light exposed through the etched portion and light exposed through the non-etched portion The phase difference is caused by the difference in the distance between the exposed light and the substrate. In an etched Levinson-type phase shift mask, it is desirable that there is no difference between the phase shift effects produced everywhere in the face of the phase shift mask. Therefore, in the case of etching a Levinson-type phase shift mask, it is desirable that the depth of each etching portion in the plane of the phase shift mask is equal. The etching portions of the phase shift mask are formed simultaneously by dry etching the substrate. Since the shape or depth of the bottom surface of each etched portion in the phase shift mask is affected by the microtrench phenomenon or the microloading phenomenon, it is not easy to use dry etching to shape the bottom surface of each etched portion. Or the depth control is the same. In recent years, with the miniaturization of the mask pattern, the pattern width of the etched portion becomes fine, and it becomes difficult to control the depth of each etched portion. On the other hand, with miniaturization, for optical reasons, a higher phase control is required, that is, a higher controllability is required for the depth of each etched portion.

In addition, the so-called micro-groove phenomenon refers to a phenomenon in which a deep etch occurs near the edge of the pattern to form a fine groove. The micro-load phenomenon refers to a phenomenon in which the depth of the etching in the case of a fine pattern varies depending on the width of the opening portion of the pattern.

The phase shift mask disclosed in Patent Document 2 is composed of light that is exposed to light transmitted through an auxiliary light-transmitting portion having a pattern formed on a transparent phase shift film containing SiO ₂ and a main that passes through the phase shift film without being patterned. A phase shift effect occurs between the exposed light of the light transmitting portion. That is, the phase shift mask disclosed in Patent Document 2 replaces the previously etched portions of the Levinson-type phase shift mask and uses a phase shift film of SiO ₂ as a phase shift pattern to generate and form the etched portions. The situation is the same with a higher phase shift effect. Further, in the phase shift mask of Patent Document 2, a transparent conductive film (etch stop film) containing Al ₂ O ₃ is provided between the transparent substrate and the phase shift film containing SiO ₂ . Regarding the etching stopper film containing Al ₂ O ₃ , when a phase shift film containing SiO ₂ is patterned, it has a high resistance to dry etching by a fluorine-based gas. Therefore, it is possible to prevent the substrate from being etched at the time of forming the pattern of the phase shift film containing SiO ₂ , improve the phase controllability, and reduce the difference in the phase shift effect in the plane of the phase shift mask.

However, the etching stopper film containing Al ₂ O ₃ tends to have low resistance to chemical liquid cleaning. During the process of manufacturing the phase shift mask from the mask substrate, the mask substrate was cleaned several times with chemical liquid. In addition, the phase shift mask after the completion is also cleaned regularly with a chemical liquid. In these cleanings, an ammonia hydrogen peroxide mixture or a TMAH (tetramethylammonium hydroxide) aqueous solution is often used as a cleaning liquid, but an etching stopper film containing Al ₂ O ₃ has low resistance to these cleaning liquids.

For example, on a light-transmitting substrate containing glass, a phase-shifting mask including an Al ₂ O ₃ -containing etching stop film and a phase-shifting film formed with a phase-shifting film may be used to clean a phase-shifting mask using an ammonia-hydrogen peroxide mixture. At this time, the light-transmitting portion exposed on the surface of the etch stop film in the phase shift mask is gradually dissolved from the surface. When the dissolution is performed, the main surface of the substrate is exposed on the light-transmitting portion. In addition, when further cleaning is performed, the etching stopper film immediately below the pattern portion of the phase shift film also gradually dissolves from the side wall side to the inner side of the phase shift film. The dissolution of the etch stop film occurs separately from the two sidewall sides of the pattern of the phase shift film, so the width of the remaining etch stop film that remains undissolved becomes smaller than the pattern width of the phase shift film. In such a state, the phenomenon that the pattern of the phase shift film falls off easily occurs.

In addition, when a phase shift mask is set on an exposure device to perform an exposure transfer on a transfer object (a resist film on a semiconductor wafer, etc.), the exposed light is transmitted from the sum of the light-transmitting substrates of the phase shift mask. The main surface provided with the phase shift pattern is incident on the main surface side of the opposite side. The exposed light incident on the light-transmitting substrate is emitted into the atmosphere through the etching stopper film at the etched portion, and is emitted into the atmosphere through the etching stopper film and the phase shift film at the non-etched portion. The optical characteristics or thickness of the phase-shifting film of the phase-shifting mask is designed on the premise that the light passing through each exposure of the etched portion and the non-etched portion passes through the etching stopper film. However, if the etching stopper film of the non-etched portion is reduced or disappeared by performing the above-mentioned cleaning on the phase shift mask, there is a difference between the light that is exposed through each of the etched portion and the non-etched portion. The phase difference cannot be the same as the design, and it becomes difficult to obtain a predetermined phase shift effect.

Furthermore, the etching stopper film containing Al ₂ O ₃ has a problem that the transmittance of the exposed light is lower than that of the synthetic quartz glass used for the material of the light-transmitting substrate of the phase shift mask. This tendency is even more pronounced when an ArF excimer laser (wavelength 193 nm) is applied to a phase shift mask of the exposed light. The etch stop film containing Al ₂ O ₃ remains in both the etched portion and the non-etched portion of the light transmitting portion during the phase-shifting mask completion stage. Decreasing the transmittance of the exposed light in the light-transmitting portion of the phase shift mask will cause the cumulative exposure of the exposed light to the transfer object per unit time to decrease. Therefore, it is necessary to lengthen the exposure time to cause a reduction in the output of the exposure transfer step in the manufacture of the semiconductor device.

The present invention has been made in order to solve the aforementioned conventional problems. That is, the object is to provide a photomask base for a phase-shifting photomask provided with an etching stopper film having a pattern-forming film such as a phase-shifting film or a light-shielding film on a light-transmitting substrate. When the cover substrate is configured to have an etching stopper interposed between the light-transmitting substrate and the pattern-forming film, resistance to dry etching using a fluorine-based gas used for patterning the pattern-forming film is used. It has higher resistance, better resistance to chemical liquid cleaning, and higher transmittance to exposed light. Another object is to provide a phase shift mask manufactured using the mask substrate. Furthermore, the object is to provide a method for manufacturing such a phase shift mask. An object of the present invention is to provide a method for manufacturing a semiconductor device using such a phase shift mask.

In order to achieve the above-mentioned problems, the present invention has the following configuration.

(Composition 1)

A photomask base, characterized in that it is provided on a main surface of a light-transmitting substrate with a light-shielding film, and is provided with an etching stop film, a phase shift film, and the light-shielding film sequentially laminated on the light-transmitting substrate Structure, the phase shift film includes a material containing silicon and oxygen, and the etch stop film includes a material containing silicon, aluminum, and oxygen.

(Composition 2)

According to the photomask substrate described in the configuration 1, the oxygen content of the etching stopper film is 60 atomic% or more.

(Composition 3)

If the photomask base according to 1 or 2 is formed, the ratio of the content of the silicon in the etching stopper film to the total content of the silicon and the aluminum based on atomic% is 4/5 or less.

(Composition 4)

According to the photomask substrate according to any one of 1 to 3, the etching stopper film includes silicon, aluminum, and oxygen.

(Composition 5)

According to the photomask substrate according to any one of the constitutions 1 to 4, the etching stopper film is formed in contact with the main surface of the transparent substrate.

(Composition 6)

In the photomask substrate according to any one of 1 to 5, the thickness of the etching stopper film is 3 nm or more.

(Composition 7)

If the photomask substrate according to any one of 1 to 6 is constituted, the phase shift film has a lower layer containing a material containing silicon and oxygen and an upper layer containing a material containing silicon, aluminum, and oxygen. Of the structure.

(Composition 8)

If the photomask base according to any one of 1 to 7 is constituted, the phase shift film has an exposure light that passes through the phase shift film and the light passes through the same distance in the air as the thickness of the phase shift film. This function generates a phase difference between 150 degrees and 200 degrees.

(Composition 9)

If the photomask base according to any one of 1 to 8 is constituted, the phase shift film has a function of transmitting exposed light at a transmittance of 95% or more.

(Composition 10)

In the photomask substrate according to any one of 1 to 9, the light-shielding film includes a material containing chromium.

(Composition 11)

The photomask substrate according to any one of 1 to 9, wherein the light-shielding film includes a material containing at least one element selected from silicon and tantalum.

(Composition 12)

The mask base according to the constitution 10 is characterized in that a hard mask film containing a material containing at least one element selected from silicon and tantalum is provided on the light shielding film.

(Composition 13)

The mask base according to the constitution 11 is characterized in that a hard mask film including a material containing chromium is provided on the light shielding film.

(Composition 14)

A phase-shifting photomask, wherein the phase-shifting film on the photomask substrate described in any one of 1 to 11 has a phase-shifting pattern and the light-shielding film has a light-shielding pattern.

(Composition 15)

A method for manufacturing a phase-shifting photomask, which is characterized in that it uses a photomask base as described in any one of 1 to 6 and has the following steps: forming a phase-shifting pattern on the light-shielding film by dry etching Step; using the above-mentioned light-shielding film having a phase-shift pattern as a photomask, and forming a phase-shift pattern on the above-mentioned phase-shifting film by dry etching using a fluorine-based gas; and forming a light-shielding band on the above-mentioned light-shielding film by dry etching Step of shading pattern.

(Composition 16)

A method for manufacturing a semiconductor device, comprising: using a phase shift mask according to the constitution 14; a resist film for exposing and transferring a pattern on the phase shift mask onto a semiconductor substrate.

(Composition 17)

A method for manufacturing a semiconductor device, comprising: using a phase shift mask manufactured by the manufacturing method of the phase shift mask described in the constitution 15; and exposing and transferring a pattern on the phase shift mask onto a semiconductor substrate. Of the resist film.

The photomask substrate of the present invention is characterized in that it is a photomask substrate for a phase-shift photomask provided with a light-shielding film on a main surface of a light-transmitting substrate, and is sequentially laminated between the light-transmitting substrate and the light-shielding film. An etch stop film and a phase shift film are provided. The phase shift film contains silicon and oxygen, and the etch stop film contains silicon, aluminum, and oxygen. With the photomask base having such a structure, the etching stopper film can simultaneously satisfy the following three characteristics: it has resistance to dry etching using a fluorine-based gas when the phase shift film is patterned, and is practically sufficient High etch stop function, high resistance to chemical cleaning, and high transmittance to exposed light.

1‧‧‧Transparent substrate

2‧‧‧ Etching stop film

2c‧‧‧etch stop pattern

3‧‧‧ phase shift film

3c, 3e‧‧‧phase shift pattern

4‧‧‧ phase shift film

4c‧‧‧Phase shift pattern

5‧‧‧ light-shielding film

5a, 5f ‧ ‧ ‧ shading pattern

6, 9‧‧‧ hard mask film

6a, 6d, 6f, 9e, 9f ‧‧‧ hard mask patterns

7a‧‧‧resist pattern

8b‧‧‧resist pattern

17f‧‧‧resist pattern

18e‧‧‧resist pattern

31‧‧‧ lower level

31c‧‧‧lower pattern

32‧‧‧upper layer (etch stop film)

32c‧‧‧Upper pattern (etch stop pattern)

101, 103, 105, 106‧‧‧ Mask base

201, 203, 205, 206‧‧‧ phase shift mask

700‧‧‧ Surface of phase shift film

701‧‧‧ Surface of opening of phase shift pattern

702‧‧‧Etching Department

900‧‧‧ pattern formation area

901‧‧‧ Shading zone formation area

Fig. 1 is a sectional view showing the structure of a mask base in the first and second embodiments of the present invention.

Fig. 2 is a sectional view showing the structure of a phase shift mask in the first and second embodiments of the present invention.

3 (a) to (g) are schematic cross-sectional views showing manufacturing steps of a phase shift mask in the first and second embodiments of the present invention.

Fig. 4 is a sectional view showing the structure of a mask base in the third and fourth embodiments of the present invention.

Fig. 5 is a sectional view showing the configuration of a phase shift mask in the third and fourth embodiments of the present invention.

6 (a) to (h) are schematic cross-sectional views showing the manufacturing steps of the phase shift mask in the third and fourth embodiments of the present invention.

Fig. 7 is a cross-sectional view showing the configuration of a mask base in a fifth embodiment of the present invention.

Fig. 8 is a sectional view showing the structure of a phase shift mask in a fifth embodiment of the present invention.

9 (a) to (g) are schematic cross-sectional views showing manufacturing steps of a phase shift mask in a fifth embodiment of the present invention.

Fig. 10 is a cross-sectional view showing the configuration of a mask base in another embodiment.

FIG. 11 is a cross-sectional view showing the configuration of a phase shift mask in another embodiment.

12 (a)-(h) are schematic cross-sectional views showing manufacturing steps of a phase shift mask in another embodiment.

First, the reasons for completing the present invention will be described. The present inventors have made intensive studies in order to solve a technical problem that an etching stopper film containing Al ₂ O ₃ has. Al ₂ O ₃ as the material of the etching stopper film has high resistance to dry etching using a fluorine-based gas, and the transmittance of light exposed to ArF excimer laser (wavelength: about 193 nm) is shown in Comparative Example 1 below. The illustration is not too high, and the resistance to the cleaning fluid used for cleaning the phase shift mask is also low. On the other hand, SiO ₂ as the main material of the light-transmitting substrate has a higher transmittance to light exposed by ArF excimer lasers, and is more resistant to the cleaning liquid used for cleaning the phase-shift mask. A high material, but a material that is easily etched by dry etching using a fluorine-based gas. Therefore, the inventors of the present inventors conducted diligent research, and as a result, they found that by forming an etching stopper film with a material composed of a mixture of Al ₂ O ₃ and SiO ₂ , the resistance to dry etching using a fluorine-based gas can be satisfied. ArF excimer laser (wavelength: about 193nm) exposure to light has a higher transmittance, the possibility of all three conditions of the tolerance to the cleaning liquid used for cleaning the phase shift mask.

The verification was performed using an etching stop film containing a material composed of a mixture of Al ₂ O ₃ and SiO _2. As a result, it was found that dry etching using a fluorine-based gas has sufficient resistance in practical applications. This film is used as an etching stop film. Make the most of it. In addition, regarding the light transmittance of the light exposed to the ArF excimer laser, it was found that the transmittance is very high as compared with an etching stopper film containing only Al ₂ O ₃ and can withstand practical applications. Furthermore, it was found that the resistance to the cleaning solution (ammonia water hydrogen peroxide mixture, TMAH, etc.) is also very high compared to the etching stopper film containing only Al ₂ O ₃ , and there is no problem in practical application. In addition, during the EB defect correction of an etch stop film containing a material composed of a mixture of Al ₂ O ₃ and SiO ₂ , a process of supplying xenon difluoride (XeF ₂ ) gas to one side and irradiating an electron beam to the part was performed. As a result, It was also found that the resistance was sufficiently high compared to the case where a material containing only SiO ₂ was used. This means that it is possible to perform the EB defect correction of the etched portion, which was difficult for the previously etched Levinson-type phase shift mask.

The results of the above efforts have drawn the following conclusions: In order to solve the technical problems of an etch stop film containing Al ₂ O ₃ , it is necessary to form an etch stop film from a material containing silicon, aluminum, and oxygen. That is, the photomask base of the present invention is characterized in that it is a photomask base for a phase shift photomask having a phase shift film and a light-shielding film on a main surface of a light-transmitting substrate, and the phase shift film contains silicon and oxygen, An etch stop film is provided between the translucent substrate and the phase shift film, and the etch stop film contains silicon, aluminum, and oxygen. Next, each embodiment of the present invention will be described.

<First Embodiment>

[Mask Substrate and Manufacturing]

Hereinafter, each embodiment will be described with reference to the drawings. In addition, the same symbols are used for the same constituent elements in each embodiment, and the description may be simplified or omitted.

The mask base of the first embodiment of the present invention is a mask base for manufacturing a Levinson-type phase shift mask. The Levinson-type phase shift mask is provided with a specific phase difference (usually a phase difference of about 180 degrees) between the two exposed lights of the two light-transmitting portions of the light-shielding pattern that respectively absorbs the exposed light by clamping. structure. By having such a structure, the diffraction light is cancelled by the interference generated between the light transmitted through the two light-transmitting portions and the two exposure portions, and the resolution of the pattern is greatly improved (this is called a phase shift effect). Also, in the case of a Levinson-type phase shift mask, the phase shift effect between the two light-transmitting parts is improved by the person who has not transmitted the light from the light-shielding pattern through the exposure. Therefore, as in the case of the binary mask, the Light-shielding film formation with higher light-shielding performance Shading pattern.

FIG. 1 shows the configuration of the mask base of the first embodiment. The photomask base 101 of the first embodiment includes an etching stopper film 2, a phase shift film 3, and a light-shielding film 5 on the main surface of the translucent substrate 1.

The translucent substrate 1 is not particularly limited as long as it has a high transmittance to the exposed light and has sufficient rigidity. In the present invention, synthetic quartz glass substrates and other various glass substrates (for example, soda lime glass, aluminosilicate glass, etc.) can be used. Among these substrates, especially the synthetic quartz glass substrate has a higher transmittance in the ArF excimer laser light (wavelength 193nm) or a shorter wavelength region, so the light of the present invention used as a high-definition transfer pattern formation The substrate of the cover base is preferred. Among them, these glass substrates are materials that are easily etched by dry etching using a fluorine-based gas. Therefore, it is significant to provide the etching stopper film 2 on the translucent substrate 1.

The etching stopper film 2 is formed of a material containing silicon, aluminum, and oxygen. This etching stopper film 2 is a residue that remains on the entire surface of the transfer pattern formation area during the completion of the phase shift mask 201 (see FIG. 2). That is, the appearance of the etching stopper film 2 also remains in the light-transmitting portion in the region that is the non-phase shift pattern 3c. Therefore, the etching stopper film 2 is preferably formed by being in contact with the translucent substrate 1 without interposing another film therebetween.

The higher the transmittance of the etching stopper film 2 to the exposed light, the better it is. However, the etching stopper film 2 also requires sufficient etching selectivity to the fluorine-based gas between the etch stopper film 2 and the translucent substrate 1. The light transmittance is set to the same transmittance as the light-transmitting substrate 1. That is, when the transmittance of the light-transmitting substrate 1 (synthetic quartz glass) to the exposed light is 100%, the transmittance of the etching stopper film 2 is less than 100%. When the transmittance of the light-transmitting substrate 1 to the exposed light is 100%, the transmittance of the etching stopper film 2 is preferably 95% or more, more preferably 96% or more, and still more preferably 97% or more.

The etching stopper film 2 preferably has an oxygen content of 60 atomic% or more. The reason for this is that in order to set the transmittance of the exposed light to the above-mentioned value or more, it is required to include in the etching stopper film 2. There is a lot of oxygen. In addition, compared with silicon that is not bonded to oxygen and silicon that is bonded to oxygen, the resistance to chemical liquid cleaning (especially, ammonia water hydrogen peroxide mixture or alkali cleaning such as TMAH) tends to be higher. It is preferable to increase the ratio of all of the silicon present in the etching stopper film 2 to those in which oxygen is in a bonded state. On the other hand, the etching stopper film 2 preferably has an oxygen content of 66 atomic% or less.

The etching stopper film 2 is preferably a ratio of the content of silicon (Si) [atomic%] to the total content of silicon (Si) and aluminum (Al) [atomic%] (hereinafter referred to as "Si / [Si + Al] Ratio ") is 4/5 or less. By setting the Si / [Si + Al] ratio of the etching stopper film 2 to 4/5 or less, the etching rate of the etching stopper film 2 for dry etching using a fluorine-based gas can be made into the etching rate of the light-transmitting substrate 1. Less than 1/3. That is, an etching selectivity ratio of 3 times or more is obtained between the translucent substrate 1 and the etching stopper film 2. The Si / [Si + Al] ratio in the etching stopper film 2 is more preferably 3/4 or less, and even more preferably 2/3 or less. When the Si / [Si + Al] ratio is 2/3 or less, the etching rate of the etching stopper film 2 for dry etching using a fluorine-based gas can be made 1/5 or less of the etching rate of the light-transmitting substrate 1. . That is, an etching selection ratio of 5 times or more is obtained between the translucent substrate 1 and the etching stopper film 2.

The etching stopper film 2 preferably has a Si / [Si + Al] ratio of silicon (Si) and aluminum (Al) of 1/5 or more. By setting the Si / [Si + Al] ratio of the etching stopper film 2 to 1/5 or more, the etching can be performed when the transmittance of the light-transmitting substrate 1 (synthetic quartz glass) to the exposed light is set to 100%. The transmittance of the stopper film 2 is 95% or more. At the same time, it can also improve the resistance to chemical liquid cleaning. The Si / [Si + Al] ratio in the etching stopper film 2 is more preferably 1/3 or more. When the Si / [Si + Al] ratio is 1/3 or more, the transmittance of the light-transmitting substrate (synthetic quartz glass) 1 to the exposed light can be set to 100% of the etching stopper film 2 The transmittance is over 97%.

The etching stopper film 2 preferably has a content of a metal other than aluminum at 2 atomic% or less, more preferably 1 atomic% or less, and more preferably a lower detection limit when performing composition analysis by X-ray photoelectron spectroscopy. Value below. The reason for this is that if the etching stopper film 2 contains a metal other than aluminum, it may cause a decrease in the transmittance to the exposed light. Again, etching The total content of elements other than silicon, aluminum, and oxygen in the stopper film 2 is preferably 5 atomic% or less, and more preferably 3 atomic% or less.

The etch stop film 2 may be formed of a material including silicon, aluminum, and oxygen. A material containing silicon, aluminum, and oxygen means, in addition to these constituent elements, only elements (helium (He), neon (Ne) that are inevitably contained in the etching stopper film 2 when forming a film by a sputtering method). ), Rare gases such as argon (Ar), krypton (Kr) and xenon (Xe), hydrogen (H), carbon (C), etc.). By making the presence of other elements bonded to silicon or aluminum in the etching stopper film 2 extremely small, the ratio of the bonding of silicon and oxygen to the bonding of aluminum and oxygen in the etching stopper film 2 can be greatly increased. Therefore, the total content of the above elements (rare gas, hydrogen, carbon, etc.) inevitably contained in the etching stopper film 2 is also preferably 3 atomic% or less. Thereby, the etching resistance of dry etching using a fluorine-based gas can be further improved, the resistance to chemical liquid cleaning can be further improved, and the transmittance of light to exposure can be further improved. The etching stopper film 2 preferably has an amorphous structure. More specifically, the etching stopper film 2 is preferably an amorphous structure including a state of a bond between silicon and oxygen and a bond between aluminum and oxygen. Thereby, the surface roughness of the etching stopper film 2 can be made good, and the transmittance of the exposed light can be improved.

The thickness of the etching stopper film 2 is preferably 3 nm or more. By forming the etching stopper film 2 with a material containing silicon, aluminum, and oxygen, even if the etching rate for a fluorine-based gas is greatly reduced, it is not completely etched. In addition, in the case of performing chemical liquid cleaning on the etching stopper film 2, the film does not decrease at all. Considering the effects of dry etching using a fluorine-based gas and the effects of chemical liquid cleaning during the manufacture of a phase-shifting photomask from a photomask substrate, it is desirable that the thickness of the etching stopper film 2 be 3 nm or more. The thickness of the etching stopper film 2 is preferably 4 nm or more, and more preferably 5 nm or more.

The etching stopper film 2 is made of a material having a high transmittance to the exposed light, and the transmittance decreases as the thickness becomes thicker. In addition, the refractive index of the etch stop film 2 is higher than that of the material forming the translucent substrate 1, and the thicker the thickness of the etch stop film 2 is, the mask pattern actually formed on the phase shift film 3 is designed (the mask pattern bias is given) Correction or OPC (Optical Proximity Correction, Optical proximity correction) or SRAF (Sub-Resolution Assist Feature) patterns. Taking these aspects into consideration, the etching stopper film 2 is preferably 20 nm or less, preferably 15 nm or less, and more preferably 10 nm or less.

The refractive index n (hereinafter, simply referred to as the refractive index n) of the light exposed by the etching stopper film 2 to the ArF excimer laser is preferably 1.73 or less, and more preferably 1.72 or less. The reason for this is to reduce the influence caused when the design is actually formed on the mask pattern of the phase shift film 3. Since the etching stopper film 2 is formed of a material containing aluminum, it cannot have the same refractive index n as that of the light-transmitting substrate 1. The etching stopper film 2 is formed with a refractive index n of 1.57 or more. On the other hand, the etching stopper film 2 preferably has an extinction coefficient k (hereinafter, abbreviated as an extinction coefficient k) of light exposed to the ArF excimer laser, which is 0.04 or less. The reason for this is to increase the transmittance of the etching stopper film 2 to the exposed light. The etching stopper film 2 is formed of a material having an extinction coefficient k of 0.000 or more.

It is preferable that the etching stopper film 2 has high composition uniformity in the thickness direction (that is, the difference in the content of each constituent element in the thickness direction is controlled within a variation range of 5 atomic%). On the other hand, the etching stopper film 2 may have a film structure having a gradient composition in the thickness direction. In this case, the composition gradient of the Si / [Si + Al] ratio on the translucent substrate 1 side of the etching stopper film 2 is preferably higher than the Si / [Si + Al] ratio on the phase shift film 3 side. The reason for this is that it is preferred that the phase shift film 3 side of the etching stopper film 2 has high resistance to dry etching using a fluorine-based gas and high chemical liquid resistance. On the other hand, the light-transmitting substrate 1 is desired. The side has a high transmittance of the exposed light.

Another film may be interposed between the translucent substrate 1 and the etching stopper film 2. In this case, other films are required to be applied to a material having a higher transmittance to the exposed light and a smaller refractive index n than the etching stopper film 2. When a phase shift mask is manufactured from a mask substrate, a layered structure of the other film and the etching stopper film 2 exists in the light-transmitting portion of the phase shift mask in a region without a pattern of the phase shift film 3. The reason is that a high transmittance of the light-transmitting portion to the exposed light is required, and the entire transmittance of the laminated structure to the exposed light must be increased. Examples of other film materials include materials containing silicon and oxygen, or materials selected from the group consisting of hafnium (Hf) and zirconium. (Zr), titanium (Ti), vanadium (V), and boron (B). Films other than the above may be formed of a material containing silicon, aluminum, and oxygen and having a higher Si / [Si + Al] ratio than the etching stopper film 2. In this case, the transmittance of the other films to the exposed light becomes high, and the refractive index n becomes small (closer to the material of the light-transmitting substrate 1).

The phase shift film 3 is a material containing silicon and oxygen, which is transparent to the exposed light, and has a specific phase difference. Specifically, the phase shift film 3 having only one light-transmitting portion among the two light-transmitting portions where the light-shielding film 5 does not exist is sandwiched between the patterns (light-shielding portions) formed by the light-shielding film 5 to form an existing phase. The light-transmitting portion of the shift film 3 and the light-transmitting portion without the phase-shift film 3 are transmitted through the existing phase with respect to the exposure light (light exposed by the ArF excimer laser) passing through the light-transmissive portion without the phase-shift film 3 The phase of the exposed light of the light-transmitting portion of the transfer film 3 becomes a substantially reversed relationship (specific phase difference). Thereby, the light that revolves to the target area mutually cancels each other by the diffraction phenomenon, so that the light intensity at the boundary portion becomes substantially zero, thereby improving the contrast at the boundary portion, that is, the resolution. In the case of a Levinson-type phase shift mask, there is a light-shielding portion at the junction, but an optical image with higher contrast is obtained by interference of light transmitted from both sides of the light-shielding portion with each other.

The phase shift film 3 preferably has a function (transmittance) of transmitting the exposed light at a transmittance of 95% or more, and the thickness of the above-exposed light passing through the phase shift film and passing through the air with the thickness of the phase shift film. The function of generating a phase difference of 150 degrees or more and 200 degrees or less between the above-exposed light at the same distance. The phase difference of the phase shift film 3 is more preferably 150 degrees or more and 180 degrees or less. From the viewpoint of improving the exposure efficiency, the light transmittance of the phase shift film 3 is more preferably 96% or more, and still more preferably 97% or more.

In recent years, when a phase shift mask is set on a mask stage of an exposure device and an exposure transfer is performed on a transfer object (resist film on a semiconductor wafer, etc.), the pattern line width based on the phase shift pattern ( In particular, the difference in the best focus of the exposure transfer of the pattern between the lines and the gap patterns becomes a problem. In order to reduce the fluctuation range of the optimal focus based on the pattern line width of the phase shift pattern, a specific phase difference of the phase shift film 3 may be set to 170 degrees or less.

The thickness of the phase shift film 3 is preferably 180 nm or less, more preferably 177 nm or less, and even more preferably 175 nm or less. On the other hand, the thickness of the phase shift film 3 is preferably 143 nm or more, and more preferably 153 nm or more.

Regarding the phase shift film 3, in order to satisfy the above-mentioned conditions of the optical characteristics and the thickness of the film, the refractive index n of the phase shift film with respect to the exposed light (ArF excimer laser light) is preferably 1.52 or more, more preferably 1.54 or more. The refractive index n of the phase shift film 3 is preferably 1.68 or less, and more preferably 1.63 or less. The extinction coefficient k of the phase shift film 3 to the light exposed by the ArF excimer laser is preferably 0.02 or less, and more preferably close to zero.

In addition, the refractive index n and the extinction coefficient k of a thin film including the phase shift film 3 are not determined only by the composition of the thin film. The film density and crystal state of the thin film are also factors that affect the refractive index n or the extinction coefficient k. Therefore, each condition when a thin film is formed by reactive sputtering is adjusted so that the thin film is formed into a film having a specific refractive index n and an extinction coefficient k. In the case of forming the phase shift film 3 by reactive sputtering, in order to become the range of the refractive index n and the extinction coefficient k, it is effective to adjust the ratio of the mixed gas of the rare gas and the reactive gas (oxygen), but Not only that. This involves various aspects such as the pressure in the film-forming chamber when forming a film by reactive sputtering, the power applied to the sputtering target, and the distance between the target and the transparent substrate 1. These film forming conditions are those inherent in the film forming apparatus, and are appropriately adjusted so that the phase shift film 3 formed has a specific refractive index n and an extinction coefficient k.

In the case of the previous Levinson phase shift mask, the translucent substrate was etched to a specific depth to form an etched portion, and each of the non-etched portion and the etched portion was adjusted according to the depth of the etched portion. Phase difference (amount of phase shift) between the exposed light. This translucent substrate is formed of synthetic quartz, and an ArF excimer laser is applied to the light to be exposed. When the phase difference is set to, for example, 180 degrees, the required depth of the etched portion is about 173 nm. In recent years, the thickness of a light-shielding film of a binary mask or a half-tone phase shifting mask of a half-tone phase shifting mask has not reached 100 nm in most cases. Compared with the case where patterns are formed on the thin films by dry etching, the case where an etched portion is formed on a light-transmitting substrate by dry etching is used. When it is shaped, the etching depth is very deep.

There is a tendency that as the depth of the etched portion formed by dry etching becomes deeper, the difference in etching rate in dry etching when forming each etched portion due to the difference in line width or shape between the etched portions is liable to change. Big. Refinement of the transfer pattern in the transfer mask is remarkable, and the line width of the etched portion becomes very thin. The thinner the line width of the etched part, the harder it is for the etching gas to enter the etched part, so the difference in etching rate between the etched parts in the plane tends to become larger.

In the previous dry etching for forming an etched portion on a light-transmitting substrate, unlike the case of patterning a phase shift film provided on the light-transmitting substrate by etching, there is no method for detecting the end point of the etching. The formation of an etched portion in a conventional etched Levinson-type phase shift mask is adjusted by using the etching time of dry etching etched from the surface of the substrate. Therefore, if the etching rate difference between the etching portions in the plane is large, there is a problem that the difference in the etching depth of the etching portions in the phase shift mask produced becomes larger, and there are in-plane differences. There may be a difference in phase shift effect.

On the other hand, in order to further improve the verticality of the sidewall of the pattern of the etched portion, the bias voltage applied during the dry etching of the transparent substrate to form the etched portion is higher than before (hereinafter referred to as "high bias" Etched "). However, this high-bias etching causes a problem that the bottom surface near the side wall of the etched portion is partially etched due to etching, so-called microgrooves, which is a problem. It is thought that the reason for the generation of the microgrooves is that due to the charging generated by applying a bias voltage to the translucent substrate, the ionized etching gas is drawn to the vicinity of the etched portion having a resistance value lower than that of the translucent substrate. The pattern side of the light-shielding film.

On the other hand, consider a case where an etching portion is not formed on the light-transmitting substrate 1, but an etching stopper film made of Al ₂ O _{3 and} a material having a high transmittance are sequentially laminated on the light-transmitting substrate 1. The phase shift film 3 is formed, and the phase shift film 3 is dry-etched to form a phase shift pattern instead of the etched portion. That is, a phase shift pattern 3c (see FIG. 2) is formed on the phase shift film 3. The structure including the side wall of the phase shift pattern 3c and the bottom surface of the etching stopper film has the same optical function as the etched portion. In this case, if the difference in the in-plane etching rate during the dry etching in which the phase shift pattern 3c is formed in the phase shift film 3 is large, the following situation will occur: the dry etching is performed at a certain position in the plane to reach the phase shift first Lower end of film 3. However, in the case where dry etching is continued on all other parts in the plane in this state until the lower end of the phase shift film 3 is reached, the etching stopper film is exposed to the etching gas even in the region where the phase shift film 3 is completely removed. The amount to be etched is also small, and the light-transmitting substrate 1 will not be dry-etched. Therefore, the uniformity in the height direction (thickness direction) of the structure including the phase shift pattern 3c and the etching stopper film finally produced is high. Therefore, the manufactured phase shift mask can reduce the difference of the phase shift effect in the plane.

In addition, by providing an etching stopper film, it is also possible to suppress microgrooves that are easily generated during high-bias etching. However, there are problems in that the chemical liquid cleaning must be performed afterwards, the etching stopper film which has low resistance to the chemical liquid cleaning is dissolved, and the phase shift pattern comes off.

In order to solve the problem of resistance to the cleaning solution of the etching stopper film, the etching stopper film 2 of the first embodiment is made of a material containing silicon, aluminum, and oxygen. Thereby, even if the phase shift film 3 is over-etched, the etching stop film 2 will not disappear, and the micro-grooves that are easily generated in high-bias etching can be suppressed, and the resistance to the subsequent chemical liquid cleaning is also reduced. When it is sufficiently high, the phenomenon that the phase shift pattern falls off can also be suppressed.

The phase shift film 3 may be composed of a single layer, or may be composed of a plurality of layers, including a material containing silicon and oxygen. By containing oxygen in the silicon, it is possible to ensure high transparency to the light exposed, and it is possible to obtain better optical characteristics as a phase shift film.

The phase shift film 3 contains a material containing silicon and oxygen as described above. However, in order to improve the transmittance or light resistance to the exposed light, and to improve the processability by dry etching, it is preferable to use materials other than silicon and oxygen. The content is 5 atomic% or less, and more preferably 3 atomic% or less. Further, a material containing silicon and oxygen is preferable, and for example, SiO _{2 is} preferable. When the phase shift film 3 is formed by the sputtering method, the film inevitably contains helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) ) And other rare gases, or hydrogen (H), carbon (C), etc. that exist in a vacuum. In this case, by optimizing the film formation conditions or annealing after film formation, it is preferable to phase The total content of these elements other than silicon and oxygen contained in the transfer film 3 is 5 atomic% or less, and more preferably 3 atomic% or less.

The phase shift film 3 of the silicon oxide-based material is formed by sputtering, and DC (direct current) sputtering, RF (radio frequency) sputtering, and ion beam sputtering can be applied. When a target having a low conductivity (a silicon target, a SiO ₂ target, etc.) is used, RF sputtering or ion beam sputtering is preferably applied, and if film formation rate is considered, RF sputtering is preferably applied.

The EB defect correction etching end point detection is performed by irradiating a black defect with an electron beam by detecting at least any one of Oje Electronics, secondary electrons, characteristic X-rays, and backscattered electrons released from the irradiated part. . For example, in the case of detecting Ogilvy electrons released from a part irradiated with an electron beam, a change in material composition is mainly observed by Ogilvy Electron Spectroscopy (AES). In the case of detecting secondary electrons, the change in surface shape is mainly observed from the SEM image. Furthermore, when detecting characteristic X-rays, changes in material composition are mainly observed by energy dispersive X-ray spectroscopy (EDX) or wavelength dispersive X-ray spectroscopy (WDX). When detecting the situation of backscattered electrons, the electron beam backscatter diffraction (EBSD) method is mainly used to observe the change in the composition or crystalline state of the material.

In a photomask base that is in contact with the main surface of a light-transmitting substrate 1 containing a glass material and is provided with a phase shift film 3 containing a material containing silicon and oxygen, the main constituent elements of the light-transmitting substrate 1 are Silicon and oxygen, so the difference between the translucent substrate 1 and the phase shift film 3 is basically only the difference between the slight composition ratio of silicon and oxygen and the difference in molecular bonding state. Therefore, it is a difficult combination to detect the end point of etching for EB defect correction. On the other hand, when the structure of the phase shift film 3 is provided in contact with the surface of the etching stop film 2, most components of the phase shift film 3 are silicon and oxygen. In contrast, the etching stop film 2 is removed. Contains aluminum in addition to silicon and oxygen. Therefore, in the etching endpoint detection of EB defect correction, as long as the aluminum detection is used as the standard, the endpoint detection becomes relatively easy.

The light-shielding film 5 may have any of a single-layer structure and a multilayer structure of two or more layers. In addition, each layer of the light-shielding film having a single-layer structure and the light-shielding film having a multilayer structure of two or more layers may be a film or The composition having substantially the same composition in the thickness direction of the layer may be a composition having a gradient composition in the thickness direction of the layer.

The mask base 101 described in FIG. 1 has a configuration in which a light-shielding film 5 is laminated on the phase shift film 3 without passing through other films. In the case of this configuration, a material having a sufficient etching selectivity to the etching gas used when the phase shift film 3 is patterned must be applied to the light-shielding film 5.

As a material satisfying this condition, in the first embodiment, a material containing chromium is used as the light shielding film 5. As the chromium-containing material for forming the light-shielding film 5, in addition to chromium metal, chromium (Cr) may be selected from the group consisting of oxygen (O), nitrogen (N), carbon (C), boron (B), and fluorine (F). ) Material of 1 or more elements. Generally, chromium-based materials are etched using a mixed gas of a chlorine-based gas and oxygen, but the etching rate of the chromium metal to the etching gas is not too high. Considering that the etching rate of an etching gas for a mixed gas of a chlorine-based gas and an oxygen gas is considered, as a material for forming the light-shielding film 5, it is preferable that chromium contains a material selected from the group consisting of oxygen, nitrogen, carbon, boron, and fluorine. Material of more than one element. In addition, the chromium-containing material forming the light-shielding film may contain one or more elements of molybdenum (Mo), indium (In), and tin (Sn). By containing one or more elements of molybdenum, indium, and tin, the etching rate of a mixed gas of chlorine-based gas and oxygen can be further accelerated.

The light-shielding film 5 containing a material containing chromium is formed by sputtering, and any sputtering such as DC sputtering, RF sputtering, and ion beam sputtering can be applied. Among them, if the film formation rate is considered, it is preferable to apply RF sputtering.

As for the light-shielding film 5, a function of shielding the exposed light with a high light-shielding rate is required. The reason is that in order to increase the exposure light transmitted through the gap portion of the phase shift pattern 3c (equivalent to the etching portion of the previously etched Levinson-type phase shift mask) and the upper non-shielding pattern 5a (see FIG. 2) The phase shift effect between the exposed portions of the pattern portion (equivalent to the previously etched light-transmitting portion of the Levinson-type phase shift mask) is preferably such that the exposed light does not pass through the light-shielding pattern 5a. In these respects, as with the binary mask, it is required to ensure an optical density (OD) of greater than 2.0 for the light-shielding film 5, preferably having an OD of 2.8 or more, and more preferably having an OD of 3.0 or more. OD. Here, as shown in FIG. 2, the light-shielding belt forming region 901 refers to a light-shielding region formed on the outside of the pattern-forming region 900 in which a pattern (circuit pattern) to be subjected to exposure transfer is formed. It is formed for the purpose of preventing adverse effects (coverage of light from exposure) caused by adjacent exposure when printing on a wafer.

In the first embodiment, a hard mask film 6 can be laminated on the light shielding film 5 (see FIG. 3). The hard mask film 6 is formed of a material having an etching selectivity for an etching gas used when the light shielding film 5 is etched. Thereby, as described below, the thickness of the resist film can be significantly reduced compared to a case where the resist film is directly used as a mask of the light shielding film 5.

As described above, the light-shielding film 5 must have a specific optical density to have a sufficient light-shielding function. Therefore, there is a limit to the reduction in thickness. On the other hand, the hard mask film 6 is sufficient as long as it has a film thickness capable of functioning as an etching mask just before the dry-etching of the light-shielding film 5 directly below it is patterned, and is basically not limited by optics. Therefore, the thickness of the hard mask film 6 can be made significantly thinner than the thickness of the light shielding film 5. In addition, as long as the resist film of the organic material has a film thickness that functions as an etching mask only before the dry etching for patterning the hard mask film 6 is completed, it is sufficient as compared with using the resist film directly. When used as a mask for the light-shielding film 5, the film thickness of the resist film can be greatly reduced. In this way, the resist film can be formed into a thin film, so that the resist resolution can be improved, and the collapse of the formed pattern can be prevented.

In this way, it is preferable to form the hard mask film 6 laminated on the light shielding film 5 from the above materials, but the present invention is not limited to this embodiment. In the mask base 101, the hard mask film 6 may not be formed, and A resist pattern is directly formed on the light-shielding film 5, and the light-shielding film 5 is directly etched using the resist pattern as a photomask.

The hard mask film 6 is preferably formed of a material containing silicon (Si) when the light shielding film 5 is formed of a material containing chromium. Here, since the hard mask film 6 in this case tends to have low adhesiveness with the resist film of the organic material, it is preferable to implement HMDS (Hexamethyldisilazane, Rokko) on the surface of the hard mask film 6. Disilazane) treatment to improve surface adhesion. The hard mask film 6 in this case is more preferably formed of SiO ₂ , SiN, SiON, or the like.

In addition, as the material of the hard mask film 6 when the light shielding film 5 is formed of a material containing chromium, a material containing tantalum (Ta) may be used. As the material containing tantalum in this case, in addition to tantalum metal, materials containing one or more elements selected from nitrogen, oxygen, boron, and carbon in tantalum can also be cited. Examples include Ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN, and the like. The hard mask film 6 in this case is preferably formed in a form not containing silicon. The allowable content of silicon is preferably 5 atomic% or less, more preferably 3 atomic% or less, and further preferably substantially free of silicon.

In the photomask base 101, a resist film of an organic material is preferably formed in contact with the surface of the hard mask film 6 with a film thickness of 100 nm or less. In the case of a fine pattern corresponding to the DRAM hp32nm generation, a SRAF (Sub-Resolution Assist Feature) having a line width of 40nm may be set in a transfer pattern (phase shift pattern) that should be formed on the hard mask film 6. That is, when this situation is facilitated, since the cross-sectional aspect ratio of the resist pattern is reduced to 1: 2.5, it is also possible to suppress the resist pattern from collapsing or detaching during development of the resist film and during washing. Furthermore, if the thickness of the resist film is 80 nm or less, the collapse or detachment of the resist pattern can be further suppressed, so it is more preferable.

The etching stopper film 2, the phase shift film 3, the light-shielding film 5, and the hard mask film 6 are formed by sputtering, and any sputtering such as DC sputtering, RF sputtering, and ion beam sputtering can be applied. When a target having a low conductivity is used, RF sputtering or ion beam sputtering is preferably applied. However, if the film formation rate is considered, RF sputtering is more preferably applied.

Regarding the film formation method of the etching stopper film 2, it is preferable to arrange two targets of a mixed target of silicon and oxygen and a mixed target of aluminum and oxygen in the film forming chamber to form the etching stopper film 2 on the translucent substrate 1. Specifically, a light-transmitting substrate 1 is arranged on a substrate stage in the film forming chamber, and each of the two targets is exposed to a rare gas environment such as argon (or a mixed gas environment with oxygen or a gas containing oxygen). A specific voltage is applied (in this case, an RF power source is preferred). As a result, the plasma-caused rare gas particles collide with two targets and cause sputtering, respectively, and an etching stopper film 2 containing silicon, aluminum, and oxygen is formed on the surface of the light-transmitting substrate 1. Furthermore, it is more preferable to use a SiO ₂ target and an Al ₂ O ₃ target as the _two targets in this case.

In addition, the etching stopper film 2 can be formed only by a mixed target of silicon, aluminum, and oxygen (preferably a mixed target of SiO ₂ and Al ₂ O ₃ , the same applies hereinafter), and a mixed target of silicon, aluminum, and oxygen can also be formed with silicon. The target, or a mixed target of aluminum and oxygen, and two targets of the aluminum target are simultaneously discharged to form an etching stopper film 2.

As described above, the mask base 101 of the first embodiment includes the etching stopper film 2 containing silicon, aluminum, and oxygen between the light-transmitting substrate 1 and the phase shift film 3. In addition, the etching stopper film 2 simultaneously satisfies the following three characteristics: the resistance to dry etching using a fluorine-based gas when the phase shift pattern is formed in the phase shift film 3 is higher than that of the light-transmitting substrate 1, and it is chemically cleaned The tolerance is also higher, and the transmittance to the exposed light is also higher. Thereby, the etching stopper film 2 can be significantly suppressed from being formed when the phase shift pattern 3c is formed in the phase shift film 3 by dry etching using a fluorine-based gas. In addition, the uniformity in the height direction (thickness direction) of each structure including the phase shift pattern 3 c formed thereon and the bottom surface of the etching stopper film 2 is greatly improved. Therefore, the uniformity of the phase shift effect of the phase shift mask 201 finally produced in the plane is high. In addition, when using the EB defect correction to correct defects in the phase shift pattern found in the middle of the manufacture of the phase shift mask, it is easy to detect the end point of the etching, so that the defects can be corrected with high accuracy.

[Phase shift mask and its manufacturing]

The phase shift mask 201 (see FIG. 2) of the first embodiment is characterized in that the etching stopper film 2 of the mask base 101 remains on the entire surface of the main surface of the transparent substrate 1 and is formed on the phase shift film 3. There is a phase shift pattern 3c, and a light-shielding pattern 5a is formed on the light-shielding film 5. When the mask base 101 is provided with the hard mask film 6, the hard mask film 6 is removed in the middle of manufacturing the phase shift mask 201 (see FIG. 3).

That is, the phase shift mask 201 of the first embodiment is characterized in that The substrate 1 is sequentially laminated with a structure including an etch stop film 2, a phase shift pattern 3c, and a light-shielding pattern 5a. The phase shift pattern 3c includes a material containing silicon and oxygen, and the etch stop film 2 includes a material containing silicon, aluminum, and oxygen.

The manufacturing method of the phase shift mask 201 of the first embodiment is characterized in that it uses the above-mentioned mask substrate 101 and includes the following steps: forming a light-shielding band including a light-shielding film by dry etching using a chlorine-based gas on the light-shielding film 5 A step of forming a light-shielding pattern 5a; and using the light-shielding film 5 with the light-shielding pattern 5a and the resist film with a resist pattern 8b as a photomask, forming a phase shift by dry etching using a fluorine-based gas on the phase-shift film 3 Step of pattern 3c (see FIG. 3).

Hereinafter, a method for manufacturing the phase shift mask 201 according to the first embodiment will be described based on the manufacturing steps shown in FIG. 3 as a cross-sectional structural view of the essential parts. Here, a method of manufacturing a phase shift mask 201 using a mask substrate 101 in which a hard mask film 6 is laminated on a light shielding film 5 will be described. In the first embodiment, a case where a material containing chromium is applied to the light-shielding film 5 and a material containing silicon is applied to the hard mask film 6 will be described.

First, it is in contact with the hard mask film 6 in the mask substrate 101 and a resist film is formed by a spin coating method. Next, for the resist film, a light-shielding pattern that should be formed on the light-shielding film 5 by electron beam drawing is further subjected to a specific process such as a development process to form a first resist pattern 7a (see FIG. 3 (a)). Next, using the first resist pattern 7a as a photomask, first dry etching using a fluorine-based gas such as CF _{4 is} performed to form a first hard mask pattern 6a on the hard mask film 6 (see FIG. 3 (b)). .

Next, after the resist pattern 7a is removed, the hard mask pattern 6a is used as a photomask, and a second dry etching using a mixed gas of a chlorine-based gas and oxygen is performed to form a first light-shielding pattern 5a on the light-shielding film 5 (see FIG. 3). (c)). By this second dry etching, the film thickness of the hard mask pattern 6a becomes thinner than the film thickness before the dry etching.

Then, a resist film is formed by a spin coating method, and then the resist film is patterned by an electron beam, and then a specific process such as a development process is performed to form a second resist pattern 8b (see FIG. 3 ( d)).

Thereafter, a third dry etching using a fluorine-based gas such as CF _{4 is} performed to form a phase shift pattern 3 c on the phase shift film 3 (see FIG. 3 (e)). In the third dry etching for the phase shift film 3, the second resist pattern 8b and the light-shielding pattern 5a become patterns for etching a mask, and it is the edge of the light-shielding pattern 5a that determines the position of the edge portion of the phase-shift pattern 3c. Therefore, the drawing transfer position accuracy (alignment accuracy) of the second resist pattern 8b can be made relatively insignificant. In addition, by the third dry etching, the hard mask pattern 6a becomes a hard mask pattern 6d which is dry-etched using the second resist pattern 8b as a photomask.

In the third dry etching using the fluorine-based gas of the phase shift film 3, in order to improve the verticality of the pattern sidewall of the phase shift pattern 3c, and to improve the CD (Critical Dimension, critical dimension) in the plane of the phase shift pattern 3c ) Uniformity, and additional etching (over-etching) is performed. After the over-etching, the surface of the etching stopper film 2 is slightly etched, and the surface 701 of the opening portion of the phase shift pattern 3c is not exposed.

Thereafter, the second resist pattern 8b is removed using an ashing or peeling solution (see FIG. 3 (f)), and then the hard mask pattern 6d remaining on the light-shielding pattern 5a is removed (see FIG. 3 (g)). ). The hard mask pattern 6d can be removed by dry etching using a fluorine-based gas. Furthermore, since the influence on the exposure transfer is small even in the state where the hard mask pattern 6d is not removed, the hard mask pattern 6d can be left in advance, but it may become a problem during the mask pattern defect inspection. The pseudo-defect generation source is preferably removed in advance.

Thereafter, a cleaning step is performed, and a mask defect inspection is performed if necessary. Furthermore, a defect correction is performed as needed according to the result of a defect inspection, and the phase shift mask 201 is manufactured. Here, the aqueous hydrogen peroxide mixture is used in the cleaning step, but the surface of the etching stopper film 2 is hardly dissolved, and the surface of the translucent substrate 1 is not exposed at the opening portion (the surface 701) of the phase shift pattern 3c.

The chlorine-based gas used in the dry etching of the light-shielding film 5 is not particularly limited as long as it contains chlorine (Cl). Examples include Cl ₂ , SiCl ₂ , CHCl ₃ , CH ₂ Cl ₂ , BCl ₃ and the like. In addition, since the photomask base 101 is provided with an etching stopper film 2 on the light-transmitting substrate 1, the fluorine-based gas used in the dry etching of the hard mask film 6 and the phase shift film 3 is not limited as long as it contains fluorine (F). No special restrictions. Examples include: CHF ₃ , CF ₄ , C ₂ F ₆ , C ₄ F ₈ , SF ₆ and the like.

The phase shift mask 201 according to the first embodiment is produced by using the mask base 101 described above. Therefore, the verticality of the side wall of the phase shift pattern 3c of the phase shift mask 201 in this embodiment 1 is high, and the uniformity of the CD in the plane of the phase shift pattern 3c is also high. The uniformity in the height direction (thickness direction) of each structure including the phase shift pattern 3c and the bottom surface of the etching stopper film 2 is also very high. Therefore, the uniformity of the phase shift effect of the phase shift mask 201 in the plane is high. In addition, during the manufacture of the phase shift mask 201, a defect was found in the phase shift pattern 3c, and when the defect was corrected by EB defect correction, the etching termination function was high, and the etching end point was easy to detect, so it could be corrected with high accuracy. defect.

[Manufacture of semiconductor device]

The method for manufacturing a semiconductor device according to the first embodiment is characterized in that the pattern for transfer is exposed and transferred using the phase shift mask 201 manufactured by using the phase shift mask 201 of the first embodiment or the mask base 101 of the first embodiment. To a resist film on a semiconductor substrate. The verticality of the side wall of the phase shift pattern 3c of the phase shift mask 201 in Embodiment 1 is higher, and the uniformity of the CD in the plane of the phase shift pattern 3c is also higher, and the uniformity of the phase shift effect in the plane is also higher. . Therefore, if the resist film on the semiconductor device is subjected to exposure transfer using the phase shift mask 201 of the first embodiment, the resist film on the semiconductor device can be patterned with sufficient accuracy to meet the design specifications.

In addition, even in a case where the phase shift mask for correcting the defects existing in the phase shift pattern 3c is used in the middle of the manufacturing process, the resist film on the semiconductor device can be exposed and transferred with high accuracy. Correcting the defects can prevent the transfer failure of the resist film on the semiconductor device corresponding to the defective phase shift pattern 3c of the phase shift mask. Therefore, in a case where a circuit pattern is formed by dry-etching a film to be processed by using the resist pattern as a photomask, there can be no wiring caused by insufficient accuracy or poor transfer. The high accuracy of short circuit or disconnection forms a circuit pattern with high yield.

In addition, the above description has been made of the case where the mask base of the first embodiment is used to manufacture a Levinson-type phase shift mask. However, the mask base of the first embodiment can be similarly applied to the use of manufacturing a CPL (Chromeless Phase Lithography) mask. The CPL photomask is a type of phase-shifting photomask that basically does not include a light-shielding film except for a large pattern area in a transfer pattern formation area. The etched part and the non-etched part of the transparent substrate constitute a transfer pattern. Generally, a CPL mask is formed on a transparent substrate with a repeating pattern of non-etched portions and etched portions. In addition, the depth of the etched portion is adjusted in such a manner that an interference effect (phase shift effect) is generated between the light transmitted through the non-etched portion and the light transmitted through the etched portion.

In the CPL mask, the light exposed through the non-etched portion is interfered by the diffracted light of each exposed light transmitted by the two etched portions holding the two sides of the non-etched portion. The amount of light becomes approximately zero, and this area becomes a dark area of the optical image transmitted through the CPL mask. The mask base of the first embodiment can replace the etched portion of the CPL mask with a structure including a pattern of the phase shift film 3 and an etching stopper film 2, so that the CPL mask can be easily manufactured. The effect of applying the mask base of the first embodiment to the manufacture of a CPL mask is the same as the case of applying the above-mentioned Levinson phase shift mask.

<Second Embodiment>

[Mask Substrate and Manufacturing]

The mask base of the second embodiment of the present invention is a mask base for a phase shift mask obtained by changing the materials of the light shielding film and the hard mask film by the user in the first embodiment. In the mask base of the second embodiment, the light-shielding film 5 is a film containing at least one element selected from silicon and tantalum, and the hard mask film 6 is a film containing chromium. The configuration of the mask base of the second embodiment is the same as that of the mask base of the first embodiment. The mask base of the second embodiment can obtain the same effects as those of the mask base of the first embodiment. The mask base of the second embodiment can be similarly applied to the production of a CPL mask. Made.

The light-shielding film 5 is required to have light-shielding properties, processability, film smoothness, mass productivity, and low defectivity.

Examples of materials having such characteristics include materials containing silicon or materials containing transition metals and silicon. A material containing a transition metal and silicon has a higher light shielding performance than a material containing no transition metal and silicon, and can reduce the thickness of the light shielding film 5. Examples of the transition metal contained in the light-shielding film 5 include molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), nickel (Ni), and vanadium. (V), zirconium (Zr), ruthenium (Ru), rhodium (Rh), niobium (Nb), palladium (Pd), or any one or more of these metals or alloys of these metals. When the light-shielding film 5 is formed of a material containing silicon, metals other than transition metals (tin (Sn), indium (In), gallium (Ga), etc.) may be contained.

The light-shielding film 5 may be formed of a material containing silicon and nitrogen or a material containing silicon and nitrogen containing one or more elements selected from the group consisting of a semi-metallic element, a non-metallic element, and a rare gas. The light-shielding film 5 in this case may contain any kind of semi-metal element. If the semi-metal element contains one or more elements selected from the group consisting of boron, germanium, antimony, and tellurium, it is expected that the conductivity of silicon used as a target will be improved when the light-shielding film 5 is formed by sputtering. good.

Regarding the light-shielding film 5, in the case of a laminated structure including a lower layer and an upper layer, the lower layer may be formed of a material containing silicon or a material containing at least one element selected from carbon, boron, germanium, antimony, and tellurium in silicon. The upper layer may be formed of a material containing silicon and nitrogen or a material containing silicon and nitrogen containing at least one element selected from semi-metallic elements, non-metallic elements and rare gases.

The light-shielding film 5 may be formed of a material containing tantalum. In this case, the content of silicon in the light-shielding film 5 is preferably 5 atomic% or less, more preferably 3 atomic% or less, and further preferably substantially free of silicon. These tantalum-containing materials are materials capable of patterning a transfer pattern by dry etching using a fluorine-based gas. As the material containing tantalum in this case, in addition to tantalum metal, there may be listed tantalum containing one or more elements selected from nitrogen, oxygen, boron, and carbon. Materials, etc. Examples include Ta, TaN, TaO, TaON, TaBN, TaBO, TaBON, TaCN, TaCO, TaCON, TaBCN, TaBOCN, and the like.

The material for forming the light-shielding film 5 may also be selected from the group consisting of oxygen (O), nitrogen (N), carbon (C), boron (B), and hydrogen (H) as long as it does not significantly reduce the optical density. More than one element. In particular, a tantalum nitride film (TaN film) containing nitrogen tends to improve the smoothness of the light-shielding film and improve the roughness of the light-shielding pattern. In addition, since Ta metal is easily oxidized in the atmosphere, if a pattern side wall including a Ta metal element is exposed after the photomask pattern is produced, the line width changes with the passage of time. When nitrogen is added to the Ta metal, it becomes difficult to be oxidized. Therefore, when tantalum (Ta) is used for the light-shielding film 5, it is preferable to contain nitrogen. In order to further improve the smoothness of the tantalum nitride film, boron, carbon, or the like may be added to the tantalum nitride film. Since these elements reduce the light-shielding performance or etching performance of the Ta metal, the addition amount is preferably 20 atomic% or less. Specifically, when boron and carbon are added, the light-shielding performance decreases. When carbon is added, the etching rate decreases.

The light-shielding film 5 may have any of a single-layer structure and a multilayer structure of two or more layers. In order to reduce the reflectance of the surface of the light-shielding film 5 on the opposite side to the light-transmitting substrate 1 to the exposed light, the surface layer on the opposite side to the light-transmitting substrate 1 (a two-layer structure of the lower layer and the upper layer) can also be made. In the case, the upper layer) contains a large amount of oxygen or nitrogen.

The hard mask film 6 is formed of a material containing chromium. The hard mask film 6 is more preferably formed of a material containing chromium and one or more elements selected from nitrogen, oxygen, carbon, hydrogen, and boron. The hard mask film 6 may contain at least one metal element selected from the group consisting of indium (In), tin (Sn), and molybdenum (Mo) in these chromium-containing materials (hereinafter, these metal elements are referred to as " Metal elements such as indium ").

[Phase shift mask and its manufacturing]

The phase shift mask of the second embodiment is the same as the phase shift mask of the first embodiment except that the material forming the light shielding film 5 is changed, and the effect obtained by this is also the same.

Method for manufacturing phase shift mask of the second embodiment and phase shift light of the first embodiment The different aspects of the manufacturing method of the mask are only the processes that must be changed due to changes in the materials forming the light-shielding film 5 and changes in the materials forming the hard mask film 6. Specifically, the first dry etching performed to form the first hard mask pattern 6 a on the hard mask film 6 uses a mixed gas of a chlorine-based gas and oxygen. The second dry etching system for forming the light-shielding pattern 5 a on the light-shielding film 5 uses a fluorine-based gas.

In the manufacturing method of the phase shift mask of the second embodiment, when the third dry etching using a fluorine-based gas is performed when the phase shift film 3 forms the phase shift pattern 3c, the pattern shape of the hard mask pattern 6a is substantially unchanged. . The reason is that the hard mask film 6 in the second embodiment is formed of a material containing chromium, and has a high etching resistance to a fluorine-based gas. The hard mask pattern 6a is responsible for protecting the light-shielding pattern 5a from being etched by a fluorine-based gas during the third dry etching.

[Manufacture of semiconductor device]

The method for manufacturing a semiconductor device according to the second embodiment is the same as the method for manufacturing a semiconductor device according to the first embodiment, except that the phase shift mask of the second embodiment is used. The effect obtained by using the phase shift mask of the second embodiment is also the same as the method of manufacturing the semiconductor device of the first embodiment.

<Third Embodiment>

[Mask Substrate and Manufacturing]

The mask base 103 (refer to FIG. 4) of the third embodiment of the present invention is one in which the phase shift film 3 of the mask base structure described in the first embodiment is a laminated phase shift film 4. That is, the laminated phase shift film 4 is composed of a lower layer 31 containing a material containing silicon and oxygen (SiO-based material) and an upper layer 32 containing a material containing silicon, aluminum, and oxygen (SiAlO-based material) and having an etching stop function. Make up. The phase shift film 4 is obtained by combining the lower layer 31 and the upper layer 32 to obtain a specific phase difference (see FIG. 4). The light-transmitting substrate 1, the etching stopper film 2, the light-shielding film 5, and the hard mask film 6 in Embodiment 3 are the same as those in Embodiment 1, and the materials and manufacturing methods are also the same. The lower layer 31 is also made of the same material as the phase shift film 3 in Embodiment 1, and uses the same method.

In the third embodiment, the lower layer 31 must provide a specific phase difference to the exposed light by using the entire phase shift film 4 of the laminated structure of the lower layer 31 and the upper layer 32. Therefore, the film thickness of the phase shift film 3 in the first embodiment is different. . If described in detail, the phase shift film 4 has a degree of 150 degrees or more and 200 degrees between the light exposed through the phase shift film 4 and the light transmitted in the air through the same distance as the thickness of the phase shift film 4. The following retardation function (preferably 150 degrees or more and 180 degrees or less) has a transmittance of at least 95% for the light to be exposed. The transmittance of the phase shift film 4 is more preferably 96% or more, and still more preferably 97% or more. Here, the film thickness of the upper layer 32 including the SiAlO-based material is 3 nm or more, preferably 4 nm or more, more preferably 5 nm or more, and 20 nm or less, preferably 15 nm or less, and more preferably 10 nm or less. On the other hand, the film thickness of the lower layer 31 including the SiO-based material is 120 nm or more, preferably 130 nm or more, more preferably 140 nm or more, and 170 nm or less, preferably 160 nm or less, and more preferably 150 nm or less. Hereinafter, the third embodiment will be described focusing on the differences from the first embodiment.

Regarding constituent elements and the like, the upper layer 32 is the same as the etching stopper film 2. The upper layer 32 and the etching stopper film 2 may be the same constituent elements and compositions, or may be different constituent elements and compositions. The upper layer 32 has both the above-mentioned phase shift function and an etching stop function that the surface of the phase shift pattern is not etched when the hard mask pattern 6d is removed. That is, the reason is to prevent the surface 700 that exposes the upper layer pattern 32c from being etched due to the etching when the hard mask pattern is removed, and the film thickness of the phase shift pattern deviates from a specific value or its surface is rough (see FIG. 6). If the film thickness deviates from a specific value, the phase difference of the phase shift pattern with respect to the exposed light may deviate from a specific value. If the surface is rough, the transmittance of the exposed light may decrease.

[Phase shift mask and its manufacturing]

In the phase shift mask 203 (see FIG. 5) of the third embodiment, in addition to the features of the first embodiment, the first feature is that the phase shift pattern 4c includes a laminated pattern of a lower layer pattern 31c and an upper layer pattern 32c. This laminated structure is a phase shift pattern that gives a specific phase difference to the light that is exposed. The second feature is that the upper layer pattern 32c has an etching stop function. A light-shielding pattern 5a is formed thereon.

That is, the phase shift mask 203 of the third embodiment is characterized in that it has a structure in which an etching stopper film 2, a phase shift pattern 4c, and a light-shielding pattern 5a are sequentially laminated on the light-transmitting substrate 1, and the phase shift pattern is provided. 4c has a structure in which a lower layer pattern 31c including a material containing silicon and oxygen and an upper layer pattern 32c including a material containing silicon, aluminum, and oxygen are sequentially stacked, and the etching stopper film 2 includes a material including silicon, aluminum, and oxygen.

The manufacturing method of the phase shift mask of the third embodiment is the one using the above-mentioned mask base 103. Hereinafter, the manufacturing method of the phase shift mask 203 of the third embodiment will be described based on the manufacturing steps shown in FIG. . Here, a case where a material containing chromium is applied to the light-shielding film 5 and a material containing silicon is applied to the hard mask film 6 will be described.

First, a first resist pattern 7a is formed (see FIG. 6 (a)), and then the resist pattern 7a is used as a photomask, and dry etching using a fluorine-based gas such as CF _{4 is} performed to form a hard mask film 6. Mask pattern 6a (see FIG. 6 (b)). Next, after removing the resist pattern 7a, dry etching using a mixed gas of a chlorine-based gas and oxygen is performed using the hard mask pattern 6a as a photomask to form a first light-shielding pattern 5a on the light-shielding film 5 (see FIG. 6 (c )).

Then, a second resist pattern 8b for forming the phase shift pattern 4c is formed (see FIG. 6 (d)). Thereafter, dry etching using a mixed gas of boron chloride (BCl ₃ ) and chlorine (Cl ₂ ) is performed to form an upper layer pattern 32c on the upper layer 32 (see FIG. 6 (e)), and then a fluorine-based gas such as CF ₄ is used. By dry etching, a lower layer pattern 31c is formed on the lower layer 31 (see FIG. 6 (f)). In this way, a phase shift pattern 4c including a lower layer pattern 31c and an upper layer pattern 32c is formed.

Thereafter, the second resist pattern 8b is removed using ashing or a stripping solution (see FIG. 6 (g)), and the remaining hard mask pattern 6d is removed by dry etching using a fluorine-based gas such as CF ₄ . The phase shift mask 203 is obtained through a specific process such as cleaning (see FIG. 6 (h)). At this time, since the surface 700 of the upper layer pattern 32c is exposed, since the material constituting it is a SiAlO-based material having an etching stop function, the surface 700 is hardly etched, and the phase shift pattern 4c can ensure exposure to light. The specific phase difference. In the cleaning step here, an ammonia hydrogen peroxide mixture is used, but the surface of the etching stopper film 2 is hardly dissolved, and the surface of the light-transmitting substrate 1 is not exposed at the light-transmitting portion of the phase shift pattern 4c. In addition, the exposed surface 700 of the upper layer pattern 32c is hardly dissolved, and the desired shape and film thickness are maintained. The chlorine-based gas and fluorine-based gas used in the dry etching are the same as those used in the first embodiment.

The lower pattern 31c of the phase shift mask 203 in Embodiment 3 occupies a higher verticality of the side wall of the main phase shift pattern 4c, and the in-plane CD uniformity is also higher, and the in-plane phase shift effect is more uniform. high. Therefore, if the resist film on the semiconductor device is exposed and transferred using the phase shift mask 203 of Embodiment 3, the resist film on the semiconductor device can be patterned with sufficient accuracy to meet the design specifications. The mask base of the third embodiment can be applied to the production of a CPL mask in the same manner as in the first embodiment.

<Fourth Embodiment>

[Mask Substrate and Manufacturing]

The mask base of the fourth embodiment of the present invention is the mask base structure described in the third embodiment, and the light shielding film 5 and the hard mask film 6 are changed to the light shielding film 5 and the hard mask described in the second embodiment. Material of the cover film 6. That is, in Embodiment 4, the light-shielding film 5 is a film containing at least one element selected from silicon and tantalum, and the hard mask film 6 is a film containing chromium. Others are the same as those of the mask base of the third embodiment. The mask base of the fourth embodiment can obtain the same effects as those of the mask base of the third embodiment. With such a configuration, the upper layer 32 serves as an etching stopper when the light shielding film 5 is etched. Therefore, the shape and in-plane CD uniformity of the light-shielding pattern 5a formed by dry etching using a fluorine-based gas is improved, and a phase shift pattern 4c having a high phase controllability can be obtained.

The light shielding film 5 of the fourth embodiment is provided in contact with the upper layer 32 of the phase shift film 4. Considering the end-of-etch detection when the EB defect correction is used to correct the light-shielding film 5, when the light-shielding film 5 is formed of a material containing silicon, it is preferable that the light-shielding film 5 does not contain aluminum.

[Phase shift mask and its manufacturing]

The phase shift mask of the fourth embodiment is the same as the phase shift mask of the third embodiment except that the material forming the light shielding film 5 is changed to the material of the light shielding film of the second embodiment, and the effect obtained by this is also the same. The manufacturing method of the phase shift mask of the fourth embodiment uses the above-mentioned mask base, and the manufacturing method of the phase shift mask of the third embodiment is different only due to changes in the material forming the light-shielding film 5 and forming a hard The process of changing the material of the mask film 6 results in a change. The process of this change is also set to be the same as the process corresponding to the method of manufacturing the phase shift mask of the second embodiment.

In the manufacturing method of the phase shift mask of the fourth embodiment, the pattern of the hard mask pattern 6a is used in the dry etching when the upper layer 32 is formed with the upper pattern 32c and the dry etching is performed in the lower layer 31 when the lower pattern 31c is formed. The shape is basically unchanged. The reason for this is that the hard mask film 6 in the fourth embodiment is formed of a material containing chromium, and has a high etching resistance to these etching gases. In addition, the hard mask pattern 6a is responsible for protecting the light-shielding pattern 5a from being etched by a fluorine-based gas during dry etching of the lower layer 31.

Here, when the light-shielding pattern 5a is formed by dry etching using a fluorine gas, the surface of the portion 700 exposed on the upper layer pattern 32c is hardly etched. In addition, the phase shift pattern 4c including the lower layer pattern 31c and the upper layer pattern 32c is a person who has ensured a specific phase difference with respect to the exposed light. In the fourth embodiment, the lower layer pattern 31c of the phase shift mask 203 occupies a higher verticality of the side wall of the main phase shift pattern 4c, and the uniformity of the CD in the plane is also higher. Higher. Therefore, if the resist film on the semiconductor device is subjected to exposure transfer using the phase shift mask 203 of Embodiment 4, the resist film on the semiconductor device can be patterned with sufficient accuracy to meet the design specifications. The mask base of the fourth embodiment can be applied to the production of a CPL mask in the same manner as in the first embodiment.

<Fifth Embodiment>

[Mask Substrate and Manufacturing]

The mask base 106 (refer to FIG. 7) of the fifth embodiment of the present invention is the one in which the hard mask film 9 is provided between the phase shift film 3 and the light shielding film 5 in the mask base structure described in the second embodiment. . The hard mask film 9 is formed of a material containing chromium similarly to the hard mask film 6. The other matters regarding the hard mask film 9 are the same as those of the hard mask film 6. The mask substrate of the fifth embodiment is particularly suitable for use in the manufacture of a CPL mask.

[Phase shift mask and its manufacturing]

The phase shift mask 206 (refer to FIG. 8) of this fifth embodiment is characterized in that it is a CPL mask and that the etching stopper film 2 of the mask base 106 remains on the entire surface of the main surface of the light-transmitting substrate 1. A phase shift pattern 3e is formed on the phase shift film 3, a hard mask pattern 9f is formed on the hard mask film 9, and a light blocking pattern 5f is formed on the light shielding film 5. The hard mask film 6 is removed in the middle of manufacturing the phase shift mask 206 (see FIG. 9).

That is, the phase shift mask 206 of the fifth embodiment is characterized by having a structure in which an etching stopper film 2, a phase shift pattern 3e, a hard mask pattern 9f, and a light shielding pattern 5f are sequentially laminated on the light-transmitting substrate 1. The phase shift pattern 3e contains a material containing silicon and oxygen, the hard mask pattern 9f contains a material containing chromium, the light-shielding film 5 contains a material containing at least one element selected from silicon and tantalum, and the etching stopper film 2 contains Materials of silicon, aluminum and oxygen.

The method of manufacturing the phase shift mask 206 of the fifth embodiment is characterized in that it uses the above-mentioned mask base 106 and has the following steps: forming a light-shielding film by dry etching using a chlorine-based gas on the hard mask film 6 Step of patterning; using a hard mask film (hard mask pattern) 6f with a light-shielding pattern as a photomask, and forming a light-shielding pattern 5f on the light-shielding film 5 by dry etching using a fluorine-based gas; by using a chlorine-based gas A step of forming a phase shift pattern on the hard mask film 9 by dry etching; using a hard mask film (hard mask pattern) 9e having a phase shift pattern as a photomask, and performing dry etching on the phase shift film using a fluorine-based gas 3 a step of forming a phase shift pattern 3e; and a step of forming a hard mask pattern 9f on the hard mask film 9e by dry etching using a chlorine-based gas using the light shielding pattern 5f as a photomask (see FIG. 9).

In the following, according to the manufacturing steps shown in FIG. A method for manufacturing the phase shift mask 206 of the fifth embodiment will be described. Here, a case where a material containing silicon is applied to the light shielding film 5 will be described.

First, it is in contact with the hard mask film 6 in the mask base 106 and a resist film is formed by a spin coating method. Next, for the resist film, a light-shielding pattern to be formed on the light-shielding film 5 is drawn using an electron beam, and then specific processing such as development processing is performed to form a resist pattern 17f (see FIG. 9 (a)). Then, using the resist pattern 17f as a photomask, dry etching using a mixed gas of a chlorine-based gas and oxygen is performed to form a hard mask pattern 6f on the hard mask film 6 (see FIG. 9 (b)).

Next, after removing the resist pattern 17f, dry etching using a fluorine-based gas such as CF _{4 is} performed using the hard mask pattern 6f as a photomask to form a light-shielding pattern 5f on the light-shielding film 5 (see FIG. 9 (c)).

Next, a resist film is formed by a spin-coating method, and then the resist film is formed with a phase shift pattern that should be formed on the phase shift film 3 by an electron beam drawing, and then specific processing such as development processing is performed to form the resist film. A resist pattern 18e (see FIG. 9 (d)).

Thereafter, dry etching using a mixed gas of a chlorine-based gas and oxygen is performed using the resist pattern 18e as a photomask to form a hard mask pattern 9e on the hard mask film 9 (see FIG. 9 (e)). Next, after removing the resist pattern 18e, dry etching using a fluorine-based gas such as CF _{4 is} performed to form a phase shift pattern 3e on the phase shift film 3 (see FIG. 9 (f)).

Then, the light-shielding pattern 5f is used as a photomask, and dry etching is performed using a mixed gas of a chlorine-based gas and oxygen to form a hard mask pattern 9f. At this time, the hard mask pattern 6f is simultaneously removed.

Thereafter, a cleaning step is performed, and a mask defect inspection is performed if necessary. Further, a defect correction is performed as necessary based on the results of the defect inspection to manufacture a phase shift mask 206. In the cleaning step here, the surface of the etching stopper film 2 is hardly dissolved using the ammonia hydrogen peroxide mixture, and the surface of the translucent substrate 1 is not exposed at the opening of the phase shift pattern 3e. In addition, the chlorine-based gas and fluorine-based gas used in the dry etching in the above-mentioned process are similar to the embodiment. The situation is the same for state 1.

The phase shift mask (CPL mask) 206 according to the fifth embodiment is manufactured using the mask base 106 described above. Therefore, the verticality of the side walls of the phase shift pattern 3e of the phase shift mask 206 in this embodiment 5 is high, and the uniformity of the CD in the plane of the phase shift pattern 3e is also high. The uniformity in the height direction (thickness direction) of each structure including the phase shift pattern 3e and the bottom surface of the etching stopper film 2 is also very high. Therefore, the uniformity of the phase shift effect of the phase shift mask 206 in the plane is high. In addition, during the manufacture of the phase shift mask 206, a defect was found in the phase shift pattern 3e, and when the defect was corrected by EB defect correction, the etching termination function was high, and the etching end point was easy to detect, so it could be corrected with high accuracy. defect.

[Manufacture of semiconductor device]

The method for manufacturing a semiconductor device according to the fifth embodiment is characterized in that the pattern for transfer is exposed and transferred by using the phase shift mask 206 of the fifth embodiment or the phase shift mask 206 manufactured by using the mask base 106 of the fifth embodiment. To a resist film on a semiconductor substrate. The verticality of the side wall of the phase shift pattern 3e of the phase shift mask 206 of Embodiment 5 is higher, and the uniformity of the CD in the plane of the phase shift pattern 3e is also higher, and the uniformity of the phase shift effect in the plane is also higher. . Therefore, if the resist film on the semiconductor device is subjected to exposure transfer using the phase shift mask 206 of Embodiment 5, the resist film on the semiconductor device can be patterned with sufficient accuracy to meet the design specifications.

In addition, in the case where the phase shift mask for correcting the defects existing in the phase shift pattern 3e is used in the middle of its manufacture to perform the exposure transfer of the resist film on the semiconductor device, it is also corrected with high accuracy. Defects can prevent a defective transfer of the resist film on the semiconductor device corresponding to the defective phase shift pattern 3e of the phase shift mask. Therefore, in a case where a circuit pattern is formed by dry-etching a film to be processed by using the resist pattern as a photomask, it is possible to form a yield with high accuracy without a short circuit or disconnection of wiring caused by insufficient accuracy or poor transfer. Higher circuit pattern.

<Another embodiment>

[Mask Substrate and Manufacturing]

The photomask base of this another embodiment is suitable for use in manufacturing an etched Levinson-type phase shift photomask. As shown in FIG. 10, the photomask base 105 has a configuration in which an etching stopper film 2 and a light-shielding film 5 are sequentially laminated on a transparent substrate 1. A hard mask film 6 is formed on the light shielding film 5 as necessary (see FIG. 12). The details of each of the light-transmitting substrate 1 and the etching stopper film 2 are the same as those in the first embodiment. As for the light-shielding film 5 and the hard mask film 6, as in the first embodiment, a combination of the light-shielding film 5 containing a material containing chromium and the hard mask film 6 containing a material containing silicon or a material containing tantalum can be applied. As for the light-shielding film 5 and the hard mask film 6, as in the second embodiment, a light-shielding film 5 including any one of a material containing silicon, a material containing transition metal and silicon, and a material containing tantalum may be applied. In combination with a hard mask film 6 containing a material containing chromium. The details of each of the light shielding film 5 and the hard mask film 6 are the same as those in the first embodiment and the second embodiment.

The photomask base 105 is provided with an etching stopper film 2 between the light-transmitting substrate 1 and the light-shielding film 5. Therefore, when the light-shielding film 5 is a material (any one of a material containing silicon, a material containing a transition metal and silicon, and a material containing tantalum) patterned by dry etching using a fluorine-based gas, it can be improved. The verticality of the side wall of the light-shielding pattern 5a can prevent micro-grooves from being generated in the light-transmitting substrate 1 near the side wall of the light-shielding pattern 5a. In addition, when the hard mask film 6 is removed by dry etching using a fluorine-based gas, the surface of the light-transmitting substrate 1 can be suppressed from being rough. If the surface is rough, the transmittance of the exposed light decreases.

[Phase shift mask and its manufacturing]

The phase shift mask 205 (refer to FIG. 11) of this another embodiment has a structure in which a light-shielding pattern 5 a is formed on the light-shielding film 5 of the mask base 105, and a pattern of the light-transmitting substrate 1 from which the pattern of the light-shielding film 5 is removed. The formation region 900 is provided with an etched portion etched from the surface at a specific depth and an unetched light-transmitting portion, respectively, and an etch stop pattern 2c is formed on the etch stop film 2 as a pattern in which only the area on the etched portion is removed. The phase shift mask 205 is adjusted in such a manner as to generate a specific phase difference between the light exposed through the etching portion and the light transmitted through the light transmitting portion. The depth of the etching of the translucent substrate 1 and the optical characteristics and film thickness of the etching stopper film 2 are adjusted. When the mask base 105 is provided with the hard mask film 6, the hard mask film 6 is removed during the production of the phase shift mask 205 (see FIG. 12).

Hereinafter, a manufacturing method of the phase shift mask 205 according to another embodiment will be described based on the manufacturing steps shown in FIG. 12 which is a cross-sectional structural diagram of the essential part. Here, a method of manufacturing a phase shift mask 205 using a mask base 105 on which a hard mask film 6 is laminated on a light shielding film 5 will be described. Here, a case where a material containing a transition metal and silicon is applied to the light shielding film 5 and a material containing chromium is applied to the hard mask film 6 will be described. The details of the etching gas and the like are the same as those in the first embodiment.

First, it is in contact with the hard mask film 6 in the mask substrate 101 and a resist film is formed by a spin coating method. Next, for the resist film, a light-shielding pattern that should be formed on the light-shielding film 5 by electron beam drawing is further subjected to a specific process such as a development process to form a first resist pattern 7a (see FIG. 12 (a)). Next, using the first resist pattern 7a as a photomask, first dry etching using a mixed gas of a chlorine-based gas and oxygen is performed to form a first hard mask pattern 6a on the hard mask film 6 (see FIG. 12 (b )).

Next, after the resist pattern 7a is removed, a second dry etching using a fluorine-based gas is performed using the hard mask pattern 6a as a photomask to form a first light-shielding pattern 5a on the light-shielding film 5 (see FIG. 12 (c)). By this second dry etching, the film thickness of the hard mask pattern 6a becomes thinner than the film thickness before the dry etching.

In the dry etching of the light-shielding film 5 using a fluorine-based gas, additional etching is performed in order to improve the verticality of the pattern sidewall of the light-shielding pattern 5a and to improve the uniformity of the CD (Critical Dimension) in the surface of the light-shielding pattern 5a. Over-etched). After the over-etching, the surface of the etching stopper film 2 is also slightly etched, and the surface 700 of the light-transmitting portion of the light-shielding pattern 5a is not exposed.

Then, a resist film is formed by a spin coating method, and thereafter, the resist film is patterned with an electron beam, and then specific processing such as development processing is performed to form a second film. The resist pattern 8b (refer to FIG. 12 (d)).

Next, a second resist pattern 8b is formed to form the etching stop pattern 2c and the etched portion 702 (see FIG. 12 (d)). Thereafter, dry etching using a mixed gas of boron chloride (BCl ₃ ) and chlorine (Cl ₂ ) is performed to form an etching stop pattern 2c on the etching stop film 2 (see FIG. 12 (e)). Next, dry etching using a fluorine-based gas such as CF _{4 is} performed to etch the translucent substrate 1 from the surface to a specific depth to form an etched portion 702 (see FIG. 12 (f)).

Thereafter, the second resist pattern 8b is removed using an ashing or peeling solution (see FIG. 12 (g)), and then the hard mask pattern 6a remaining on the light-shielding pattern 5a is removed (see FIG. 12 (h). )). The hard mask pattern 6a can be removed by dry etching of a mixed gas of a chlorine-based gas and an oxygen gas.

Thereafter, a cleaning step is performed, and a mask defect inspection is performed if necessary. Further, if necessary, defect correction is performed based on the results of the defect inspection, and a phase shift mask 205 is manufactured. Here, an ammonia hydrogen peroxide mixture is used in the cleaning step, but the surface of the etching stopper film 2 is hardly dissolved, and the surface of the light-transmitting substrate 1 is not exposed at the light-transmitting portion (the surface 700) of the etching stopper pattern 2c.

The phase shift mask 205 of this another embodiment is manufactured using the mask base 105 mentioned above. Therefore, the verticality of the sidewall of the light-shielding pattern 5a of the phase-shifting mask 205 in this other embodiment is high, and the uniformity of the CD in the plane of the light-shielding pattern 5a is also high. In addition, during the manufacture of the phase shift mask 205, a black defect was found in the light-shielding pattern 5a. When the black defect was corrected by EB defect correction, the etching termination function was high. Since the end point of the etching was easy to detect, it could be corrected with high accuracy. Black defect.

[Manufacture of semiconductor device]

The method for manufacturing a semiconductor device according to another embodiment is characterized in that: a phase shift mask 205 manufactured in another embodiment or a phase shift mask 205 manufactured using a mask base 105 in another embodiment is used for transferring The pattern exposure is transferred to a resist film on the semiconductor substrate. The verticality of the side wall of the light shielding pattern 5a of the phase shift mask 205 in another embodiment is High, the uniformity of CD in the plane of the light-shielding pattern 5a is also high. Therefore, if the resist film on the semiconductor device is subjected to exposure transfer using the phase shift mask 205 of another embodiment, the resist film on the semiconductor device can be patterned with sufficient accuracy to meet the design specifications.

In addition, in the case where a phase shift mask that corrects black defects existing in the light-shielding pattern 5a by using EB defect correction in the middle of its manufacture is exposed and transferred to a resist film on a semiconductor device, the black is also corrected with high accuracy. Defects can prevent a defective transfer of the resist film on the semiconductor device corresponding to the defective light-shielding pattern 5a of the phase shift mask. Therefore, in a case where a circuit pattern is formed by dry-etching a film to be processed by using the resist pattern as a photomask, it is possible to form a yield with high accuracy without a short circuit or disconnection of wiring caused by insufficient accuracy or poor transfer. Higher circuit pattern.

[Example]

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples.

(Example 1)

[Manufacture of photomask substrate]

A light-transmitting substrate 1 including a synthetic quartz glass having a size of about 152 mm × about 152 mm and a thickness of about 6.35 mm was prepared. This light-transmitting substrate 1 is a person who grinds an end surface and a main surface to a specific surface roughness or less (the root-mean-square roughness Rq is 0.2 nm or less), and then performs a specific cleaning treatment and a drying treatment.

Next, an etching stopper film 2 (AlSiO film) containing aluminum, silicon, and oxygen was formed to a thickness of 10 nm so as to be in contact with the surface of the light-transmitting substrate 1. Specifically, a translucent substrate 1 is provided in a monolithic RF sputtering device, and an Al ₂ O ₃ target and a SiO ₂ target are simultaneously discharged, and sputtering (RF) using argon (Ar) gas as a sputtering gas is performed. Sputtering) to form an etching stopper film 2. An analysis using an X-ray photoelectron spectroscopy method was performed on an etching stopper film formed on another transparent substrate under the same conditions, and the result was Al: Si: O = 21: 19: 60 (atomic% ratio). That is, the Si / [Si + Al] of this etching stopper film 2 is 0.475. Furthermore, in the analysis using the X-ray photoelectron spectroscopy method, numerical correction was performed based on the results of the RBS analysis (analysis using the Rasefort backscatter method) (the same applies to the following analysis).

Further, each optical characteristic of the etching stopper film 2 was measured using a spectroscopic ellipsometer (M-2000D manufactured by J.A. Woollam Co., Ltd.). As a result, the refractive index n under light having a wavelength of 193 nm was 1.625, and the extinction coefficient k was 0.0000 (the lower limit of measurement).

Next, a phase shift film 3 containing SiO ₂ containing silicon and oxygen was formed in a thickness of 173 nm so as to be in contact with the surface of the etching stopper film 2. Specifically, a light-transmitting substrate 1 after forming an etching stopper film 2 is provided in a monolithic RF sputtering device. A silicon dioxide (SiO ₂ ) target is used, and an argon (Ar) gas (pressure = 0.03 Pa) is set. For sputtering gas, the power of the RF power source was set to 1.5 kW, and a phase shift film 3 containing SiO _{2 was} formed by RF sputtering on the etching stopper film 2 to a thickness of 173 nm. Furthermore, for the main surface of another transparent substrate, only the phase shift film 3 containing SiO ₂ was formed under the same conditions, and the optical characteristics of the uppermost layer were measured using the above-mentioned spectroscopic ellipsometer. As a result, the refractive index n at a wavelength of 193 nm It was 1.563, and the extinction coefficient k was 0.0000 (the lower limit of measurement).

Thereafter, a light-shielding film 5 containing chromium was formed in a thickness of 59 nm so as to be in contact with the surface of the phase shift film 3. This light-shielding film 5 is a CrOC film containing oxygen and carbon in addition to chromium. Specifically, a light-transmitting substrate 1 in which a phase-shift film 3 is formed is provided in a monolithic DC sputtering apparatus, and a chromium (Cr) target is used in a mixed gas environment of carbon dioxide (CO ₂ ) and helium (He). The light-shielding film 5 is formed by the following reactive sputtering (DC sputtering).

Next, the light-transmitting substrate 1 on which the light-shielding film 5 (CrOC film) is formed is subjected to a heat treatment. Specifically, heat treatment was performed using a heating plate, setting the heating temperature to 280 ° C., and the heating time to 5 minutes in the atmosphere.

The light-shielding film 5 after the heat treatment was analyzed by X-ray photoelectron spectroscopy (with ESCA and RBS correction). As a result, it was confirmed that there is a composition gradient portion having a larger amount of oxygen content in a region (a region from the surface to a depth of about 2 nm from the surface) near the surface on the side opposite to the light-transmitting substrate 1 of the light-shielding film 5 than the other regions (The oxygen content is 40 atomic% or more). In addition, it can be seen that each of the constituent elements in a region other than the composition gradient portion of the light-shielding film 5 The content is Cr: 71 atomic%, O: 15 atomic%, and C: 14 atomic% as an average. Furthermore, it was confirmed that the difference of each constituent element in the thickness direction of the region other than the composition gradient portion of the light-shielding film 5 is 3 atomic% or less, and there is substantially no composition gradient in the thickness direction.

The composition of films other than those shown below was obtained by X-ray photoelectron spectroscopy (with ESCA and RBS correction) in the same manner as the light-shielding film 5 described above.

In addition, the optical density (OD) at a wavelength (approximately 193 nm) of the light of the ArF excimer laser was measured with a spectrophotometer (Cary4000 manufactured by Agilent Technologies) for the light-shielding film 5 after the heat treatment, and the result was confirmed to be 3.0 or more .

Next, a hard mask film 6 containing SiO ₂ containing silicon and oxygen was formed in a thickness of 12 nm so as to be in contact with the surface of the light shielding film 5. Specifically, a light-transmitting substrate 1 after forming a light-shielding film 5 is provided in a monolithic RF sputtering apparatus, a silicon dioxide (SiO ₂ ) target is used, and an argon (Ar) gas (pressure = 0.03 Pa) is set as The sputtering gas was set to 1.5 kW from the RF power source, and a hard mask film 6 containing SiO _{2 was} formed on the light-shielding film 5 by RF sputtering to a thickness of 12 nm. According to the above procedure, the mask substrate of Example 1 was manufactured.

In addition, the transmittance at the wavelength (193 nm) of the ArF excimer laser of the etching stopper film 2 formed on the other translucent substrate was measured using the phase shift amount measuring device. As a result, it was found that the transmissive substrate 1 was transmitted. When the transmittance is set to 100%, the transmittance is 98.3%, and the influence of the decrease in transmittance by providing the etching stopper film 2 of the first embodiment is small. The translucent substrate 1 on which the etching stopper film 2 was formed was immersed in ammonia water having a concentration of 0.5% to measure the etching rate. As a result, it was 0.1 nm / min. Based on the results, it can be confirmed that the etching stopper film 2 of Example 1 is sufficiently resistant to the chemical liquid cleaning performed in the process of manufacturing the phase shift mask from the mask substrate.

For each of the light-transmitting substrate 1, the etching stopper film 2 formed on the other light-transmitting substrate 1, and the phase shift film 3 formed on the other light-transmitting substrate 1, etching using CF _{4 is} performed under the same conditions. Dry etching of gas. Then, the respective etching rates were calculated and the etching selection ratios were compared. The etching selection ratio of the etching stopper film 2 of Example 1 with respect to the etching rate of the phase shift film 3 was 0.11. On the other hand, the etching selection ratio of the light-transmitting substrate 1 used in Example 1 with respect to the etching rate of the phase shift film 3 is approximately 1, and it can be seen that the etching stop film 2 of Example 1 has a sufficiently high etching stop function. .

[Manufacture and evaluation of phase shift mask]

Next, using the mask substrate 101 of the first embodiment, the phase shift mask 201 of the first embodiment is manufactured in the following order. First, the surface of the hard mask film 6 is subjected to HMDS treatment. Then, a resist film including a chemically amplified resist for electron beam drawing was formed at a film thickness of 80 nm so as to be in contact with the surface of the hard mask film 6 by a spin coating method. Next, the resist film is subjected to electron beam drawing and specific development processing is performed to form a first resist pattern 7a (see FIG. 3 (a)).

Next, dry etching using CF ₄ gas is performed using the first resist pattern 7 a as a photomask to form a first hard mask pattern 6 a on the hard mask film 6 (see FIG. 3 (b)).

Next, the first resist pattern 7a is removed by TMAH. Next, using the hard mask pattern 6a as a mask, dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1) is performed to form a first light-shielding pattern 5 a on the light-shielding film 5 (see FIG. Figure 3 (c)).

Next, the mask substrate having the hard mask pattern 6a with a thin film is subjected to HMDS treatment, and a treatment for improving the adhesion with the resist by hydrophobicizing the surface of the hard mask pattern 6a is performed. Then, a resist film including a chemically amplified resist for electron beam drawing was formed at a film thickness of 300 nm by a spin coating method so as to be in contact with the surface of the hard mask pattern 6a or the phase shift film 3 exposed on the surface. . Next, an electron beam drawing is performed on the resist film, and a specific development process is performed to form a second resist pattern 8b (see FIG. 3 (d)). Here, a program defect is added in advance to the second resist pattern 8b in order to form a defect in the phase shift film in addition to the phase shift pattern that should be formed.

Next, dry etching using CF ₄ gas is performed using the second resist pattern 8 b and the light-shielding pattern 5 a as a photomask to form a phase shift pattern 3 c on the phase shift film 3 (see FIG. 3 (e)). At the initial stage of the etching, the hard mask pattern 6a formed on the light-shielding pattern 5a also becomes an etching mask, but since the material of the hard mask and the material of the phase shift film 3 are both SiO ₂ , the hard mask pattern 6a becomes a hard mask pattern 6d in which a part of the pattern is etched and disappeared in the early stage.

In this dry etching of the phase shift film 3 using a fluorine-based gas (CF ₄ gas), except for the beginning of the phase shift film 3 to the time when the etching proceeds in the thickness direction of the phase shift film 3 and the surface of the etching stop film 2 starts Except for the etching time (appropriate etching time) until exposure, additional etching (over-etching) is performed for only 20% of the appropriate etching time (over-etching time). In addition, the dry etching using a fluorine-based gas is applied with a bias voltage at a power of 25 W, and is performed under the condition of a so-called high-bias etching.

Next, the second resist pattern 8b is removed by ashing. However, it is also possible to use TMAH instead of ashing. Then, the hard mask pattern 6d is removed by dry etching using a fluorine-based gas (CF ₄ gas).

A mask pattern inspection device was used to inspect the mask pattern of the Levinson-type phase shift mask 201 of Example 1. As a result, a defect was confirmed in the phase shift pattern 3c of the portion where the program defect was arranged. For this defective portion, the EB defect correction using an electron beam and XeF ₂ gas is performed. As a result, the etching end point can be easily detected, and the etching of the surface of the etching stopper film 2 can be controlled to a minimum.

Using another photomask base made by the method of Example 1, a Ravenson-type phase shift photomask was manufactured in the same order, and the uniformity of the CD in the plane of the phase shift pattern was checked, which was a good result. In addition, the cross section of the phase shift pattern was observed by STEM. As a result, the verticality of the side wall of the phase shift pattern was high, and the etching of the etching stop film was not as small as 1 nm, and micro grooves were not generated. Therefore, it can be said that the in-plane uniformity of the phase shift effect of the Levinson-type phase shift mask of Example 1 is high. In addition, it is also known that a Levinson-type phase shift mask having high in-plane uniformity can be produced from the mask base of Example 1 with a phase shift effect.

Regarding the Levinson-type phase shift mask 201 of Example 1 after the EB defect correction, AIMS193 (manufactured by Carl Zeiss) was used to perform exposure transfer on the resist film on the semiconductor device using light with an exposure wavelength of 193nm. Simulation of the time transfer image. To the model The proposed exposure and transfer image was verified, and the results fully met the design specifications. The decrease in the transmittance of the light-transmitting portion caused by the provision of the etching stopper film 2 has a small effect on the exposure transfer. In addition, the transfer image of the portion subjected to the EB defect correction is not inferior to the transfer image of the other region. Based on the results, it can be said that even if the Ravenson type phase shift mask of Example 1 after the EB defect correction is set on the mask stage of the exposure device, the resist film on the semiconductor device can be exposed and transferred, and finally it can be transferred. A circuit pattern formed on a semiconductor device is formed with high accuracy.

(Example 2)

[Manufacture of photomask substrate]

The photomask base of the second embodiment is manufactured in the same manner as the photomask base of the first embodiment except for the material composition of the etching stopper film 2. Therefore, on the light-transmitting substrate 1, a structure of a mask base including an etching stopper film 2, a phase shift film 3, and a light-shielding film 5 and a material of the light-transmitting substrate 1, phase-shift film 3, and light-shielding film 5 are sequentially laminated. Or the manufacturing method is the same as in Example 1. Hereinafter, portions different from the mask base of Example 1 will be described.

The etching stopper film 2 of this embodiment 2 is provided with a light-transmitting substrate 1 in a single-chip RF sputtering device, so that the Al ₂ O ₃ target and the SiO ₂ target are simultaneously discharged, and RF sputtering using argon as a sputtering gas is used. The plated AlSiO film has an element ratio of Al: Si: O = 13: 26: 61 (atomic% ratio). Therefore, the Si / [Si + Al] of the etching stopper film 2 is 0.67. The etching stopper film 2 is formed in a thickness of 10 nm so as to be in contact with the surface of the transparent substrate 1. The optical constant of the etching stopper film 2 was measured by a spectroscopic ellipsometer. As a result, the refractive index n under light with a wavelength of 193 nm was 1.600, and the extinction coefficient k was 0.0000 (the lower limit of measurement).

The transmittance at the wavelength (193 nm) of the ArF excimer laser of the etching stopper film 2 was measured by the same method as in Example 1. As a result, the transmittance was 99.4 when the transmittance of the translucent substrate 1 was set to 100%. %, The decrease in transmittance due to the provision of the etching stopper film 2 of this embodiment 2 is small. The transmissive substrate on which the etching stopper film 2 was formed was immersed in ammonia water having a concentration of 0.5% to measure the etching rate. As a result, the etching rate was 0.1 nm / min. According to this As a result, it was confirmed that the etching stopper film 2 of Example 2 has sufficient resistance to the chemical liquid cleaning performed in the process of manufacturing the phase shift mask.

In addition, using the same method as in Example 1, the etching selection ratio of the etching stopper film 2 of Example 2 with respect to the etching rate of the phase shift film 3 in the dry etching using CF ₄ etching gas was investigated, and the result was 0.24. The etch stop film 2 of 2 has a sufficiently high etch stop function in practical applications.

[Manufacture and evaluation of phase shift mask]

Next, using the mask substrate 101 of the second embodiment, a phase shift mask 201 of the second embodiment is manufactured in the same order as that of the first embodiment. The EB defect correction using the electron beam and XeF ₂ gas is performed for the program defect portion arranged in the phase shift pattern 3c. As a result, the etching end point can be easily detected, and the etching of the surface of the etching stopper film 2 can be controlled to a minimum.

The uniformity of the CD in the phase of the phase shift pattern 3c of the manufactured phase shift mask 201 and the verticality of the side wall cross section are high, and the etching of the etching stopper film 2 is not as small as 1 nm, and micro grooves are not generated. AIMS193 was used to simulate the exposure and transfer image when using this phase shift mask. As a result, the design specifications were fully met, including the case of EB defect correction.

(Example 3)

The mask base of the third embodiment is manufactured in the same manner as the mask base of the first embodiment except for the material composition of the etching stopper film 2. Therefore, on the light-transmitting substrate 1, a structure of a mask base including an etching stopper film 2, a phase shift film 3, and a light-shielding film 5 and a material of the light-transmitting substrate 1, phase-shift film 3, and light-shielding film 5 are sequentially laminated. Or the manufacturing method is the same as in Example 1. Hereinafter, portions different from the mask base of Example 1 will be described.

The etching stopper film 2 of this embodiment 3 is provided with a light-transmitting substrate 1 in a monolithic RF sputtering device, so that the Al ₂ O ₃ target and the SiO ₂ target are simultaneously discharged, and RF sputtering using argon as a sputtering gas is used. An AlSiO film formed by plating, and its element ratio is set to Al: Si: O = 7: 28: 65 (atomic% ratio). Therefore, Si / [Si + Al] of the etching stopper film 2 is 0.8. The etching stopper film 2 is formed in a thickness of 10 nm so as to be in contact with the surface of the transparent substrate 1. The optical constant of the etching stopper film 2 was measured with a spectroscopic ellipsometer. As a result, the refractive index n under light having a wavelength of 193 nm was 1.589, and the extinction coefficient k was 0.0000 (the lower limit of measurement).

The transmittance at the wavelength (193 nm) of the ArF excimer laser of the etching stopper film 2 was measured by the same method as in Example 1. As a result, when the transmittance of the translucent substrate 1 was set to 100%, the transmittance was 99.8 %, The decrease in transmittance due to the provision of the etching stopper film 2 of the third embodiment is small. The transmissive substrate on which the etching stopper film 2 was formed was immersed in ammonia water having a concentration of 0.5% to measure the etching rate. As a result, the etching rate was 0.1 nm / min. Based on the results, it can be confirmed that the etching stopper film 2 of Example 3 is sufficiently resistant to the chemical liquid cleaning performed in the process of manufacturing the phase shift mask.

In addition, using the same method as in Example 1, the etching selection ratio of the etching stopper film 2 of Example 3 with respect to the etching rate of the phase shift film 3 in dry etching using CF ₄ etching gas was investigated, and the result was 0.42. Example The etch stop film 3 of 3 has a higher etch stop function that can withstand the practical application.

[Manufacture and evaluation of phase shift mask]

Next, using the mask substrate 101 of the third embodiment, the phase shift mask 201 of the third embodiment is manufactured in the same order as that of the first embodiment. The EB defect correction using the electron beam and XeF ₂ gas is performed for the program defect portion arranged in the phase shift pattern 3c. As a result, the etching end point can be easily detected, and the etching of the surface of the etching stopper film 2 can be controlled to a minimum.

The uniformity of the CD in the phase of the phase shift pattern 3c of the manufactured phase shift mask 201 and the verticality of the side wall cross section are high, and the etching of the etching stopper film 2 is not as small as 1 nm, and micro grooves are not generated. AIMS193 was used to simulate the exposure and transfer image when using this phase shift mask. As a result, the design specifications were fully met, including the case of EB defect correction.

(Example 4)

[Manufacture of photomask substrate]

The mask base of this Example 4 was manufactured in the same manner as the mask base of Example 1 except for the material composition of the etching stopper film 2. Therefore, etching is sequentially laminated on the light-transmitting substrate 1 The structures of the mask base of the engraving stop film 2, the phase shift film 3, and the light shielding film 5, and the materials or manufacturing methods of the light-transmitting substrate 1, the phase shift film 3, and the light shielding film 5 are the same as those of the first embodiment. Hereinafter, portions different from the mask base of Example 1 will be described.

The etching stopper film 2 of the fourth embodiment is provided with a light-transmitting substrate 1 in a single-chip RF sputtering device, so that the Al ₂ O ₃ target and the SiO ₂ target are simultaneously discharged, and RF sputtering using argon as a sputtering gas is used. An AlSiO film formed by plating, and the element ratio is set to Al: Si: O = 31: 8: 61 (atomic% ratio). Therefore, the Si / [Si + Al] of the etching stopper film 2 is 0.20. The etching stopper film 2 is formed in a thickness of 10 nm so as to be in contact with the surface of the transparent substrate 1. The optical constant of the etching stopper film 2 was measured by a spectroscopic ellipsometer. As a result, the refractive index n under light with a wavelength of 193 nm was 1.720, and the extinction coefficient k was 0.0328.

The transmittance at the wavelength (193 nm) of the ArF excimer laser of the etching stopper film 2 was measured by the same method as in Example 1. As a result, it was found that the transmittance when the transmittance of the translucent substrate 1 was 100% 95.2%, the reduction in transmittance caused by the provision of the etching stopper film 2 of this embodiment 4 is a range that can withstand practical applications. The transmissive substrate on which the etching stopper film 2 was formed was immersed in ammonia water having a concentration of 0.5% to measure the etching rate. As a result, the etching rate was 0.2 nm / min. From this result, it can be confirmed that the etching stopper film 2 of Example 4 has sufficient resistance to the chemical liquid cleaning performed in the process of manufacturing the phase shift mask.

In addition, using the same method as in Example 1, the etching selection ratio of the etching stopper film 2 of Example 4 with respect to the etching rate of the phase shift film 3 in the dry etching using CF ₄ etching gas was investigated, and the result was 0.035. Example The etch stop film 2 of 4 has a sufficiently high etch stop function.

[Manufacture and evaluation of phase shift mask]

Next, using the mask substrate 101 of the fourth embodiment, a phase shift mask 201 of the fourth embodiment is manufactured in the same order as that of the first embodiment. The EB defect correction using the electron beam and XeF ₂ gas is performed for the program defect portion arranged in the phase shift pattern 3c. As a result, the etching end point can be easily detected, and the etching of the surface of the etching stopper film 2 can be controlled to a minimum.

The uniformity of the CD in the phase of the phase shift pattern 3c of the manufactured phase shift mask 201 and the verticality of the side wall cross section are high, and the etching of the etching stopper film 2 is not as small as 1 nm, and micro grooves are not generated. AIMS193 was used to simulate the exposure and transfer image when using this phase shift mask. As a result, the design specifications were fully met, including the case of EB defect correction.

(Example 5)

[Manufacture of photomask substrate]

The mask base 101 of the fifth embodiment corresponds to the embodiment of the second embodiment, and has a structure of a mask base having an etching stopper film 2, a phase shift film 3, and a light shielding film 5 laminated on the light-transmitting substrate 1 in this order. . Further, a hard mask film 6 containing CrN is formed on the light shielding film 5. The materials or manufacturing methods of the light-transmitting substrate 1, the etching stopper film 2, and the phase shift film 3 are the same as those of the first embodiment, and the light-shielding film 5 and the hard mask film 6 are different from the first embodiment. The light-shielding film 5 of Example 5 contains a Si-containing material including a laminated structure of MoSiN in the lower layer and MoSiN in the upper layer. Hereinafter, with respect to the mask base of Example 5, a part different from the mask base of Example 1 will be described.

The light-shielding film 5 of the fifth embodiment is a laminated structure film including the lower MoSiN layer and the upper MoSiN layer as described above, and the laminated film is produced in the following manner. Here, the lower MoSiN layer mainly has an absorption function (light-shielding function) of the exposed light, and the upper MoSiN layer has an anti-surface reflection function for the exposed light and the mask pattern defect inspection light.

On the phase shift film 3, a MoSiN layer (lower layer (light-shielding layer)) was formed with a film thickness of 47 nm, and then a MoSiN layer (upper layer (anti-reflective layer)) was formed with a film thickness of 4 nm, thereby forming an ArF excimer laser ( The light-shielding film 5 (wavelength 193 nm) was used (total film thickness 51 nm). Specifically, after the light-transmitting substrate 1 on which the phase shift film 3 is formed is set in a single-chip sputtering apparatus, a sputtering target is a mixed target of molybdenum (Mo) and silicon (Si) (atomic% ratio Mo: Si = 13: 87), under a mixed gas environment of argon and nitrogen, a MoSiN film (lower layer (light-shielding layer)) was formed with a thickness of 47 nm by reactive sputtering (DC sputtering), and then a Mo / Si target was used. (Atomic% ratio Mo: Si = 13: 87), a MoSiN film (upper layer (anti-reflective layer)) was formed with a film thickness of 4 nm under a mixed gas environment of argon and nitrogen.

Next, the light-transmitting substrate 1 on which the light-shielding film 5 was formed was subjected to 30 minutes at 450 ° C. The heating process (annealing process) is performed to reduce the film stress of the light-shielding film 5. Furthermore, a substrate provided with the light-shielding film 5 subjected to the annealing process was manufactured in the same order, and analyzed by X-ray photoelectron spectroscopy (ESCA) (where the analysis value was corrected by RBS). Atomic%, Si: 68.3 atomic%, N: 22.5 atomic%), and the upper layer near the lower layer side (Mo: 5.8 atomic%, Si: 64.4 atomic%, N: 27.7 atomic%, O: 2.1 atomic%). Furthermore, as a result of X-ray photoelectron spectroscopy (ESCA) analysis of the upper surface layer, nitrogen was 14.4 atomic% and oxygen was 38.3 atomic%. The refractive index n of the lower layer of the light-shielding film 5 to light of 193 nm is 1.88, and the extinction coefficient k is 2.20. The refractive index n of the upper layer is 2.07, and the extinction coefficient k is 1.14. The light-shielding film 5 has an optical density (OD) of 3.0, and the light-shielding film has a function of sufficiently shielding ArF excimer laser light.

After the light-shielding film 5 is produced, a hard mask film 6 (CrN film) containing chromium and nitrogen is formed to a thickness of 5 nm so as to be in contact with the surface of the upper layer of the light-shielding film 5. Specifically, a light-transmitting substrate 1 provided with a light-shielding film 5 after heat treatment is provided in a single-chip DC sputtering apparatus. A chromium (Cr) target is used, and argon (Ar) and nitrogen (N ₂ ) are used. Reactive sputtering (DC sputtering) of the mixed gas as a sputtering gas forms the hard mask film 6. The hard mask film formed on another transparent substrate under the same conditions was analyzed by X-ray photoelectron spectroscopy, and the result was Cr: N = 72: 28 (atomic% ratio). The photomask substrate of Example 5 was manufactured in the above order.

[Manufacture and evaluation of phase shift mask]

Next, using the mask substrate 101 of the fifth embodiment, the phase shift mask 201 of the fifth embodiment is manufactured in the same order as that of the first embodiment. The manufacturing steps are different from those in Example 1 only in the steps related to the light-shielding film 5 and the hard mask film 6. Therefore, this point will be described here.

In Example 5, a hard mask pattern 6a for forming a light-shielding pattern 5a is formed on the hard mask film 6 by dry etching using a mixed gas of chlorine and oxygen (gas flow ratio Cl ₂ : O ₂ = 4: 1). (See Fig. 3 (b)).

In addition, a light-shielding pattern 5a is formed on the light-shielding film 5 by dry etching using a fluorine-based gas (a mixed gas of SF ₆ and He) with the hard mask pattern 6a as an etching mask (see FIG. 3 (c)). In addition, the dry etching using a fluorine-based gas is applied with a bias voltage at a power of 10 W, and is performed under the condition of a so-called high-bias etching.

In the removal step of the hard mask pattern 6d (refer to FIG. 3 (g)), the hard mask is dried by dry etching using a mixed gas of a chlorine-based gas and an oxygen gas (gas flow ratio Cl ₂ : O ₂ = 4: 1). The pattern 6d is removed. The other steps are based on the process of Example 1.

The phase-shifting mask 201 produced in Example 5 has the same effect as the phase-shifting mask 201 in Example 1 because the etching stopper film 2 including an AlSiO film is formed on the translucent substrate 1. That is, the uniformity of the CD in the phase of the phase shift pattern 3c and the verticality of the side wall cross section are high, and the etching of the etching stopper film 2 is not as small as 1 nm, and micro grooves are not generated. In addition, the defects of the phase shift pattern 3c can be corrected with high accuracy by using the EB defect correction. The chemical liquid washing resistance also has the same resistance as in Example 1, and no abnormalities such as pattern peeling accompanying chemical liquid washing were observed. AIMS193 was used to simulate the exposure and transfer image when using this phase shift mask. As a result, the design specifications were fully met, including the case of EB defect correction.

(Example 6)

[Manufacture of photomask substrate]

The mask base 103 of the sixth embodiment corresponds to the third embodiment, and has an etch stop film 2, a lower layer 31, an upper layer 32 having an etch stop function, and a light-shielding film sequentially laminated on the transparent substrate 1. Structure of the mask base of 5 (see FIG. 4). Further, a hard mask film 6 is formed on the light shielding film 5. The materials or manufacturing methods of the translucent substrate 1, the etching stopper film 2, the lower layer 31, the light-shielding film 5, and the hard mask film 6 are the same as those in the first embodiment. The difference from Embodiment 1 is the film thickness of the lower layer 31 and the introduction of the upper layer 32 including AlSiO with an etching stop function. Hereinafter, with respect to the mask base of Example 6, a part different from the mask base of Example 1 will be described.

The lower layer 31 containing SiO ₂ containing silicon and oxygen is formed in a thickness of 166 nm so as to be in contact with the surface of the etching stopper film 2. The film formation conditions were the same as in Example 1, and the film formation time was controlled to obtain the film thickness. Since the film was formed under the same conditions as in Example 1, the refractive index n at the wavelength of 193 nm of the lower layer 31 was 1.563, and the extinction coefficient k was 0.0000 (the lower limit of measurement).

Then, an upper layer 32 (AlSiO film) containing aluminum, silicon, and oxygen and having an etching stop function is formed in a thickness of 5 nm so as to be in contact with the surface of the lower layer 31. The film formation conditions are the same as those of the etching stopper film 2, so the composition of the constituent elements is also the same as that of the etching stopper film 2. It is Al: Si: O = 21: 19: 60 (atomic% ratio), and Si / [Si + Al] is 0.475. . The upper layer 32 and the lower layer 31, which also have a part of a phase shift function, form a phase shift film 4 with a multilayer structure that inverts the phase of the exposed light.

The upper layer 32 is a film with the same composition as the etching stopper film 2. Therefore, according to the result of Example 1, the upper layer 32 of Example 6 has sufficient resistance to the chemical liquid cleaning performed during the process of manufacturing the phase shift mask from the mask base. Accepted. The upper layer 32 has a phase shift function, and therefore having sufficient resistance to chemical liquid cleaning is of great significance from the viewpoint of improving phase controllability.

[Manufacture and evaluation of phase shift mask]

Next, using the mask base 103 of the sixth embodiment, the phase shift mask 203 of the sixth embodiment is manufactured in the same order as that of the first embodiment. The manufacturing steps are different from those in the first embodiment only in the steps associated with the upper layer 32 and the hard mask film 6, and therefore the description will be made around this point.

In Example 6, the upper layer pattern 32c is formed by using the second resist pattern 8b and the hard mask pattern 6a as a photomask, and by using a mixed gas of boron chloride (BCl ₃ ) and chlorine (Cl ₂ ) Dry etching is performed (see FIG. 6 (e)).

The hard mask pattern 6d is removed by dry etching using a fluorine-based gas (CF ₄ gas) (see FIG. 6 (h)). The other steps are based on the process of Example 1.

Since the phase shift mask 203 produced in Example 6 has an etching stopper film 2 including an AlSiO film formed on the light-transmitting substrate 1, it has the same phase shift mask 201 as that in Example 1. The same effect. In addition, the upper layer 32 also has a sufficient etching stop function for the etching of the fluorine-based gas. Therefore, when dry etching is performed to remove the hard mask pattern 6d, it is hardly etched and does not cause surface roughness. Therefore, the phase shift pattern 4c including the lower-layer pattern 31c and the upper-layer pattern 32c is a phase-shift pattern with extremely high accuracy that imparts a specific phase difference to the exposed light (ArF excimer laser light).

The phase shift mask 203 of Example 6 is made of a material having sufficient resistance to the cleaning chemical liquid, and therefore has sufficient chemical liquid cleaning resistance. No abnormalities such as pattern peeling accompanying the chemical liquid cleaning were observed. . In order to confirm, using AIMS193 to simulate the exposure and transfer image when using this phase shift mask, the results fully satisfied the design specifications including the case of EB defect correction.

(Example 7)

[Manufacture of photomask substrate]

The mask base 103 of the seventh embodiment corresponds to the embodiment of the fourth embodiment, and has a structure of a mask base having a light-transmitting substrate 1, an etching stopper film 2, a lower layer 31, an upper layer 32, and a light-shielding film 5 laminated in this order. . Further, a hard mask film 6 containing CrN was formed on the light shielding film 5 in the same manner as in Example 5. The materials or manufacturing methods of the light-transmitting substrate 1, the lower layer 31, the upper layer 32, and the light-shielding film 5 as constituent members are the same as those in the fifth embodiment. The upper layer 32 is a film having an etching stop function for a fluorine-based gas containing AlSiO having a composition ratio of Al: Si: O = 21: 19: 60 (atomic% ratio). The upper layer 32 and the lower layer 31 together form a phase shift film 4 having a multilayer structure in which the phase of the exposed light is inverted.

[Manufacture and evaluation of phase shift mask]

Next, using the mask base 103 of the seventh embodiment, the phase shift mask 203 of the seventh embodiment is manufactured in the same order as that of the fifth embodiment. The manufacturing steps differ from the embodiment 5 only in the steps associated with the upper layer 32, so this point is described here.

In Example 7, dry etching using a fluorine-based gas (a mixed gas of SF ₆ and He) was performed using the hard mask pattern 6 a as a mask, and a light-shielding pattern 5 a was formed on the light-shielding film 5 (see FIG. 6 (c)). . In addition, the dry etching using a fluorine-based gas is applied with a bias voltage at a power of 10 W, and is performed under the condition of a so-called high-bias etching. Since the light-shielding pattern 5a formed on the upper layer 32 functions as a sufficient etch stop layer, sufficient over-etching may be performed during the formation of the light-shielding pattern 5a as needed to become a vertical cross-sectional shape and a higher in-plane CD. In this etching, the surface 700 exposed by the upper layer 32 is hardly etched, and the phase controllability as a phase shift film can be kept high.

Regarding the formation of the upper layer pattern 32c, as in Example 6, the second resist pattern 8b and the hard mask pattern 6a were used as a photomask, and a mixture of boron chloride (BCl ₃ ) and chlorine (Cl ₂ ) was used. Gas dry etching is performed (see FIG. 6 (e)).

Since the phase shift mask 203 produced in Example 7 has an etching stopper film 2 including an AlSiO film formed on the light-transmitting substrate 1, it has the same properties as those shown in the phase shift mask 201 in Example 1. effect. In addition, the upper layer 32 also has a sufficient etching stop function for the etching of the fluorine-based gas, and during dry etching when the light-shielding pattern 5a is formed, it is hardly etched and does not cause surface roughness. Therefore, the lower-layer pattern 31c and the upper-layer pattern 32c are phase shift patterns with extremely high accuracy that give a specific phase difference to the exposed light (ArF excimer laser light). In addition, the light-shielding pattern 5a is expected to have high in-plane CD uniformity and a cross-sectional side wall shape that is nearly vertical.

In addition, the phase shift mask 203 of Example 7 is made of a material having sufficient resistance to the cleaning chemical liquid, and therefore has sufficient chemical liquid cleaning resistance, and no pattern peeling accompanying the chemical liquid cleaning was observed. And so on. In order to confirm, using AIMS193 to simulate the exposure and transfer image when using this phase shift mask, the results fully satisfied the design specifications including the case of EB defect correction.

(Comparative example 1)

[Manufacture of photomask substrate]

The mask base of Comparative Example 1 has the same configuration as the mask base of Example 1 except that the etching stopper film is formed of a material containing aluminum and oxygen. The etching stopper film of Comparative Example 1 is an AlO film containing aluminum and oxygen and formed in a thickness of 10 nm so as to be in contact with the surface of the transparent substrate 1. Specifically, a translucent substrate 1 is provided in a monolithic RF sputtering apparatus, and an Al ₂ O ₃ target is used to form an etching stopper by RF sputtering using argon as a sputtering gas. An analysis using an X-ray photoelectron spectroscopy method was performed on an etching stopper film formed on another transparent substrate under the same conditions. As a result, Al: O = 42: 58 (atomic% ratio). Therefore, Si / [Si + Al] of the etching stopper film is zero. The optical constant of the etch stop film was measured using a spectroscopic ellipsometer. As a result, the refractive index n under light of a wavelength of 193 nm was 1.864, and the extinction coefficient k was 0.0689.

The transmittance at the wavelength (193 nm) of the ArF excimer laser of the etch stop film was measured by the same method as in Example 1. As a result, it was found that the transmittance when the transmittance of the translucent substrate 1 was 100% 91.7%, the influence of the decrease in transmittance due to the provision of the etching stopper film of Comparative Example 1 was relatively large. The light-transmitting substrate on which the etching stop film was formed was immersed in ammonia water having a concentration of 0.5% to measure the etching rate. As a result, the etching rate was 4.0 nm / min. From this result, it is understood that the etching stopper film of Comparative Example 1 does not have sufficient resistance to the chemical liquid cleaning performed in the process of manufacturing the phase shift mask from the mask base.

In addition, using the same method as in Example 1, the etching selection ratio of the etching stopper film of Comparative Example 1 with respect to the etching rate of the phase shift film in dry etching using CF ₄ etching gas was investigated, and the result was 0.015. The etch stop film has a sufficient etch stop function.

[Manufacture and evaluation of phase shift mask]

Next, using the mask base of Comparative Example 1, a phase shift mask of Comparative Example 1 was produced in the same procedure as in Example 1. A mask inspection device was used to inspect the mask pattern of the produced Levinson type phase shift mask of Comparative Example 1. As a result, a large number of defects other than program defects were detected. Each defect site was investigated, and most of the results were defects caused by the phase shift pattern falling off. Furthermore, the EB defect correction using an electron beam and XeF ₂ gas was performed on the defective portion of the portion where the program defect was arranged. As a result, the etching end point could be easily detected, and the etching of the surface of the etching stopper film could be minimized. .

Using another photomask substrate, a phase shift mask was manufactured in the same order. For the part where the phase shift pattern did not fall off, the cross section of the phase shift pattern was observed by STEM. Dissolution in cleaning), the etch stop film immediately below the area where the phase shift pattern is present is also dissolved from the side wall side of the phase shift pattern to the inside. Based on the results, it can be presumed that the main reason for the dissolution of the etching stopper film by chemical liquid cleaning is that a large amount of phase shift patterns are peeled off.

Regarding the Ravenson-type phase shift mask of Comparative Example 1 after the EB defect correction, AIMS193 (manufactured by Carl Zeiss) was used to expose and transfer the resist film on the semiconductor device under exposure light having a wavelength of 193 nm. Simulation of the time transfer image. Verification of the simulated exposure transfer image failed to meet the design specifications. It was found that a large number of portions where the normal exposure transfer could not be performed due to the peeling of the phase shift pattern. In addition, it can be seen that the accuracy of the transferred image is reduced due to the low transmittance of the etch stop film to the ArF excimer laser light at the portion where the phase shift pattern itself is formed with high accuracy. Based on the results, it is speculated that the case where the phase shift mask of Comparative Example 1 is set on the mask stage of an exposure device and the resist film on the semiconductor device is subjected to exposure transfer regardless of the presence or absence of EB defect correction, is finally formed in A large number of circuit patterns are disconnected or shorted on the circuit patterns on the semiconductor device.

Claims (21)

A photomask substrate, characterized in that it is provided with a structure in which an etching stop film, a phase shift film, and a light shielding film are sequentially laminated on a light-transmitting substrate, and the phase shift film includes a material containing silicon and oxygen. The etch stop film is a single-layer film including a material containing silicon, aluminum, and oxygen. For example, the mask substrate of claim 1, wherein the oxygen content of the etching stop film is 60 atomic% or more. For example, the photomask substrate of claim 1 or 2, wherein the ratio of the content of the silicon in the etching stopper film to the total content of the silicon and the aluminum based on atomic% is 4/5 or less. For example, the photomask substrate of claim 1 or 2, wherein the difference in the content of each constituent element in the thickness direction of the above-mentioned etching stopper film is within 5 atomic%. For example, the photomask substrate of claim 1 or 2, wherein the etching stopper film has an amorphous structure, and the amorphous structure includes a state of bonding between silicon and oxygen and a bond of aluminum and oxygen. For example, the photomask substrate of claim 1 or 2, wherein the etching stopper film is substantially composed of silicon, aluminum, and oxygen. For example, the photomask substrate of claim 1 or 2, wherein the above-mentioned etch stop film comprises a material obtained by mixing Al ₂ O ₃ and SiO ₂ . For example, the photomask base of claim 1 or 2, wherein the etching stopper film is formed in contact with the main surface of the transparent substrate. For example, the mask substrate of claim 1 or 2, wherein the thickness of the above-mentioned etch stop film is 3 nm or more. For example, the photomask substrate of claim 1 or 2, wherein the phase shift film has a structure in which a lower layer including a material containing silicon and oxygen and an upper layer including a material containing silicon, aluminum, and oxygen are sequentially laminated. As claimed in the photomask substrate of item 1 or 2, wherein the phase shift film has a degree of 150 degrees between light exposed through the phase shift film and light exposed in air through the same distance as the thickness of the phase shift film. The function of phase difference above and below 200 degrees. For example, the photomask substrate of claim 1 or 2, wherein the phase shift film has a function of transmitting the exposed light at a transmittance of 95% or more. The photomask substrate according to claim 1 or 2, wherein the light-shielding film comprises a material containing chromium. The photomask substrate according to claim 1 or 2, wherein the light-shielding film comprises a material containing at least one element selected from silicon and tantalum. The mask substrate according to claim 13, wherein a hard mask film including a material containing at least one element selected from silicon and tantalum is provided on the light-shielding film. The mask substrate according to claim 14, wherein a hard mask film containing a material containing chromium is provided on the light-shielding film. A phase shift mask, characterized in that the phase shift film on the mask base according to any one of claims 1 to 14 has a phase shift pattern, and the light shielding film has a light blocking pattern. A method for manufacturing a photomask substrate, which is characterized in that it is a method for manufacturing a photomask substrate having a structure in which an etching stop film, a phase shift film, and a light shielding film are sequentially laminated on a light-transmitting substrate, and has the following steps: A silicon-containing target and an aluminum-containing target are arranged in a film-forming chamber, the light-transmitting substrate is arranged on a substrate table, and sputtering is performed by applying a voltage to both the silicon-containing target and the aluminum-containing target, thereby forming a substrate containing silicon. A step of forming the above-mentioned etching stopper film containing silicon, aluminum, and oxygen; a step of forming the phase shifting film on the etching stopper film; the phase shifting film is a single-layer film containing a material including silicon and oxygen. A method for manufacturing a phase-shifting photomask, which is characterized by using a photomask substrate according to any one of claims 1 to 9 and having the following steps: forming a phase-shifting pattern on the light-shielding film by dry etching Step; using the above-mentioned light-shielding film having a phase-shift pattern as a photomask, and forming a phase-shift pattern on the above-mentioned phase-shifting film by dry etching using a fluorine-based gas; and forming a light-shielding band on the above-mentioned light-shielding film by dry etching Step of shading pattern. A method for manufacturing a semiconductor device, comprising: a step of exposing and transferring a pattern on the phase shift mask to a resist film on a semiconductor substrate using a phase shift mask as described in claim 17; A method for manufacturing a semiconductor device, comprising: using a phase shift mask manufactured by the method for manufacturing a phase shift mask according to claim 19; and exposing and transferring a pattern on the phase shift mask onto a semiconductor substrate. Of the resist film.